SELECT 
  SQL_CALC_FOUND_ROWS (
    CASE WHEN products.parent_product_id <> 0 THEN products.parent_product_id ELSE products.product_id END
  ) AS product_id, 
  IF(
    shared_descr.product_id IS NOT NULL, 
    shared_descr.product, descr1.product
  ) as product, 
  companies.company as company_name, 
  GROUP_CONCAT(
    products.product_id 
    ORDER BY 
      products.parent_product_id ASC, 
      products.product_id ASC
  ) AS product_ids, 
  GROUP_CONCAT(
    products.product_type 
    ORDER BY 
      products.parent_product_id ASC, 
      products.product_id ASC
  ) AS product_types, 
  GROUP_CONCAT(
    products.parent_product_id 
    ORDER BY 
      products.parent_product_id ASC, 
      products.product_id ASC
  ) AS parent_product_ids, 
  products.product_type, 
  products.parent_product_id, 
  1 as instock_marker, 
  IF(
    products.product_type = 'C', 
    (
      SELECT 
        MAX(amount) 
      FROM 
        cscart_products 
      WHERE 
        parent_product_id = products.product_id
    ) > 0, 
    IF(
      products.amount > 0, 
      1, 
      IF(products.tracking = 'O', 1, 0)
    )
  ) as instock_sorting 
FROM 
  cscart_products as products 
  LEFT JOIN cscart_product_descriptions as descr1 ON descr1.product_id = products.product_id 
  AND descr1.lang_code = 'ru' 
  LEFT JOIN cscart_product_prices as prices ON prices.product_id = products.product_id 
  AND prices.lower_limit = 1 
  LEFT JOIN cscart_companies AS companies ON companies.company_id = products.company_id 
  INNER JOIN cscart_products_categories as products_categories ON products_categories.product_id = products.product_id 
  INNER JOIN cscart_categories ON cscart_categories.category_id = products_categories.category_id 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
  AND cscart_categories.storefront_id IN (0, 1) 
  LEFT JOIN cscart_ult_product_descriptions shared_descr ON shared_descr.product_id = products.product_id 
  AND shared_descr.company_id = 1 
  AND shared_descr.lang_code = 'ru' 
  LEFT JOIN cscart_images_links as img_links ON img_links.object_id = products.product_id 
  AND img_links.object_type = 'product' 
  AND img_links.type = 'M' 
WHERE 
  1 
  AND cscart_categories.category_id IN (844, 755, 828) 
  AND companies.status IN ('A') 
  AND (
    products.usergroup_ids = '' 
    OR FIND_IN_SET(0, products.usergroup_ids) 
    OR FIND_IN_SET(1, products.usergroup_ids)
  ) 
  AND products.status IN ('A') 
  AND prices.usergroup_id IN (0, 0, 1) 
  AND img_links.pair_id > 0 
  AND (
    1 
    AND products.product_id IN (
      7574, 6855, 8238, 20396, 10468, 7673, 
      9496, 13033, 7181, 9780, 9796, 9794, 
      10805, 9529, 18159, 9351, 6964, 10156, 
      10549, 11010, 11014, 11013, 11018, 
      6894, 6896, 12818, 12750, 20303, 20304, 
      20305, 19788, 20306, 20776, 20781, 
      20782, 20032, 19951, 23067, 23066, 
      18458, 18452, 18713, 13467, 22527, 
      23339, 21130, 9804, 21081, 9296, 19924, 
      6939, 8346, 21555, 21556, 21557, 21559, 
      21561, 21563, 21564, 21558, 21560, 
      21562, 13416, 6863, 7646, 18834, 18836, 
      13699, 13692, 20147, 18797, 6664, 7003, 
      7004, 7006, 7007, 7010, 7075, 7540, 
      7963, 8023, 8037, 8093, 8099, 8101, 
      8110, 8140, 8144, 8148, 8151, 8157, 
      8192, 8204, 8205, 8231, 9806, 10140, 
      10201, 10286, 10413, 10685, 11634, 
      11638, 12598, 12857
    )
  ) 
GROUP BY 
  product_id 
ORDER BY 
  instock_sorting DESC, 
  product asc, 
  products.product_id ASC 
LIMIT 
  0, 24

Query time 0.00187

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "sort_key": "if(products.product_type = 'C',(subquery#2) > 0,if(products.amount > 0,1,if(products.tracking = 'O',1,0))) desc, if(shared_descr.product_id is not null,shared_descr.product,descr1.product), products.product_id",
      "temporary_table": {
        "filesort": {
          "sort_key": "case when products.parent_product_id <> 0 then products.parent_product_id else products.product_id end",
          "temporary_table": {
            "nested_loop": [
              {
                "table": {
                  "table_name": "companies",
                  "access_type": "system",
                  "possible_keys": ["PRIMARY"],
                  "rows": 1,
                  "filtered": 100
                }
              },
              {
                "table": {
                  "table_name": "cscart_categories",
                  "access_type": "range",
                  "possible_keys": ["PRIMARY", "c_status", "p_category_id"],
                  "key": "PRIMARY",
                  "key_length": "3",
                  "used_key_parts": ["category_id"],
                  "rows": 3,
                  "filtered": 100,
                  "index_condition": "cscart_categories.category_id in (844,755,828)",
                  "attached_condition": "(cscart_categories.usergroup_ids = '' or find_in_set(0,cscart_categories.usergroup_ids) or find_in_set(1,cscart_categories.usergroup_ids)) and cscart_categories.`status` in ('A','H') and cscart_categories.storefront_id in (0,1)"
                }
              },
              {
                "table": {
                  "table_name": "products_categories",
                  "access_type": "ref",
                  "possible_keys": ["PRIMARY", "pt"],
                  "key": "PRIMARY",
                  "key_length": "3",
                  "used_key_parts": ["category_id"],
                  "ref": ["lillyshop_lillyshop.cscart_categories.category_id"],
                  "rows": 26,
                  "filtered": 100,
                  "using_index": true
                }
              },
              {
                "table": {
                  "table_name": "products",
                  "access_type": "eq_ref",
                  "possible_keys": ["PRIMARY", "status"],
                  "key": "PRIMARY",
                  "key_length": "3",
                  "used_key_parts": ["product_id"],
                  "ref": ["lillyshop_lillyshop.products_categories.product_id"],
                  "rows": 1,
                  "filtered": 90.50141144,
                  "index_condition": "products.product_id in (7574,6855,8238,20396,10468,7673,9496,13033,7181,9780,9796,9794,10805,9529,18159,9351,6964,10156,10549,11010,11014,11013,11018,6894,6896,12818,12750,20303,20304,20305,19788,20306,20776,20781,20782,20032,19951,23067,23066,18458,18452,18713,13467,22527,23339,21130,9804,21081,9296,19924,6939,8346,21555,21556,21557,21559,21561,21563,21564,21558,21560,21562,13416,6863,7646,18834,18836,13699,13692,20147,18797,6664,7003,7004,7006,7007,7010,7075,7540,7963,8023,8037,8093,8099,8101,8110,8140,8144,8148,8151,8157,8192,8204,8205,8231,9806,10140,10201,10286,10413,10685,11634,11638,12598,12857)",
                  "attached_condition": "products.company_id = 1 and (products.usergroup_ids = '' or find_in_set(0,products.usergroup_ids) or find_in_set(1,products.usergroup_ids)) and products.`status` = 'A'"
                }
              },
              {
                "table": {
                  "table_name": "shared_descr",
                  "access_type": "eq_ref",
                  "possible_keys": ["PRIMARY", "product_id", "company_id"],
                  "key": "PRIMARY",
                  "key_length": "13",
                  "used_key_parts": ["product_id", "lang_code", "company_id"],
                  "ref": [
                    "lillyshop_lillyshop.products_categories.product_id",
                    "const",
                    "const"
                  ],
                  "rows": 1,
                  "filtered": 100,
                  "attached_condition": "trigcond(shared_descr.lang_code = 'ru')"
                }
              },
              {
                "table": {
                  "table_name": "descr1",
                  "access_type": "eq_ref",
                  "possible_keys": ["PRIMARY", "product_id"],
                  "key": "PRIMARY",
                  "key_length": "9",
                  "used_key_parts": ["product_id", "lang_code"],
                  "ref": [
                    "lillyshop_lillyshop.products_categories.product_id",
                    "const"
                  ],
                  "rows": 1,
                  "filtered": 100,
                  "attached_condition": "trigcond(descr1.lang_code = 'ru')"
                }
              },
              {
                "table": {
                  "table_name": "prices",
                  "access_type": "ref",
                  "possible_keys": [
                    "usergroup",
                    "product_id",
                    "lower_limit",
                    "usergroup_id"
                  ],
                  "key": "usergroup",
                  "key_length": "3",
                  "used_key_parts": ["product_id"],
                  "ref": ["lillyshop_lillyshop.products_categories.product_id"],
                  "rows": 1,
                  "filtered": 99.99145508,
                  "attached_condition": "prices.lower_limit = 1 and prices.usergroup_id in (0,0,1)",
                  "using_index": true
                }
              },
              {
                "table": {
                  "table_name": "img_links",
                  "access_type": "ref",
                  "possible_keys": ["PRIMARY", "object_id"],
                  "key": "object_id",
                  "key_length": "81",
                  "used_key_parts": ["object_id", "object_type", "type"],
                  "ref": [
                    "lillyshop_lillyshop.products_categories.product_id",
                    "const",
                    "const"
                  ],
                  "rows": 1,
                  "filtered": 100,
                  "index_condition": "img_links.object_id = products_categories.product_id and img_links.object_type = 'product' and img_links.`type` = 'M'",
                  "attached_condition": "img_links.pair_id > 0"
                }
              }
            ],
            "subqueries": [
              {
                "expression_cache": {
                  "state": "uninitialized",
                  "query_block": {
                    "select_id": 2,
                    "nested_loop": [
                      {
                        "table": {
                          "table_name": "cscart_products",
                          "access_type": "ALL",
                          "possible_keys": ["idx_parent_product_id"],
                          "rows": 11707,
                          "filtered": 100,
                          "attached_condition": "cscart_products.parent_product_id = products.product_id"
                        }
                      }
                    ]
                  }
                }
              }
            ]
          }
        }
      }
    }
  }
}