SELECT 
  cscart_discussion_posts.*, 
  cscart_discussion_messages.message, 
  cscart_discussion_messages.cp_pr_title, 
  cscart_discussion_messages.cp_pr_advantages, 
  cscart_discussion_messages.cp_pr_disadvantages, 
  cscart_discussion_rating.rating_value, 
  cscart_discussion.* 
FROM 
  cscart_discussion_posts 
  INNER JOIN cscart_discussion ON cscart_discussion.thread_id = cscart_discussion_posts.thread_id 
  INNER JOIN cscart_discussion_messages ON cscart_discussion_messages.post_id = cscart_discussion_posts.post_id 
  INNER JOIN cscart_discussion_rating ON cscart_discussion_rating.post_id = cscart_discussion_posts.post_id 
  LEFT JOIN cscart_products ON cscart_products.product_id = cscart_discussion.object_id 
  LEFT JOIN cscart_products_categories ON cscart_products_categories.product_id = cscart_discussion.object_id 
  LEFT JOIN cscart_categories ON cscart_categories.category_id = cscart_products_categories.category_id 
WHERE 
  1 
  AND cscart_discussion_posts.status = 'A' 
  AND cscart_discussion.object_id IN (7555, 7555) 
  AND cscart_discussion.object_type = 'P' 
  AND cscart_discussion_posts.cp_pr_user_delete = 'N' 
  AND cscart_discussion.type != 'D' 
  AND cscart_discussion.company_id = 1 
  AND cscart_products.status = 'A' 
  AND cscart_categories.status = 'A' 
GROUP BY 
  cscart_discussion_posts.post_id 
ORDER BY 
  cscart_discussion_posts.timestamp desc 
LIMIT 
  0, 10

Query time 0.00149

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "sort_key": "cscart_discussion_posts.`timestamp` desc",
      "temporary_table": {
        "nested_loop": [
          {
            "table": {
              "table_name": "cscart_discussion",
              "access_type": "const",
              "possible_keys": ["PRIMARY", "object_id", "idx_company_id"],
              "key": "object_id",
              "key_length": "10",
              "used_key_parts": ["object_id", "object_type", "company_id"],
              "ref": ["const", "const", "const"],
              "rows": 1,
              "filtered": 100
            }
          },
          {
            "table": {
              "table_name": "cscart_products",
              "access_type": "const",
              "possible_keys": ["PRIMARY", "status"],
              "key": "PRIMARY",
              "key_length": "3",
              "used_key_parts": ["product_id"],
              "ref": ["const"],
              "rows": 1,
              "filtered": 100
            }
          },
          {
            "table": {
              "table_name": "cscart_discussion_posts",
              "access_type": "ref",
              "possible_keys": ["PRIMARY", "thread_id", "thread_id_2"],
              "key": "thread_id_2",
              "key_length": "6",
              "used_key_parts": ["thread_id", "status"],
              "ref": ["const", "const"],
              "rows": 1,
              "filtered": 100,
              "index_condition": "cscart_discussion_posts.`status` = 'A'",
              "attached_condition": "cscart_discussion_posts.thread_id <=> 8164 and cscart_discussion_posts.`status` <=> 'A' and cscart_discussion_posts.cp_pr_user_delete = 'N'"
            }
          },
          {
            "table": {
              "table_name": "cscart_discussion_messages",
              "access_type": "eq_ref",
              "possible_keys": ["PRIMARY"],
              "key": "PRIMARY",
              "key_length": "3",
              "used_key_parts": ["post_id"],
              "ref": ["lillyshop_lillyshop.cscart_discussion_posts.post_id"],
              "rows": 1,
              "filtered": 100
            }
          },
          {
            "table": {
              "table_name": "cscart_discussion_rating",
              "access_type": "eq_ref",
              "possible_keys": ["PRIMARY"],
              "key": "PRIMARY",
              "key_length": "3",
              "used_key_parts": ["post_id"],
              "ref": ["lillyshop_lillyshop.cscart_discussion_posts.post_id"],
              "rows": 1,
              "filtered": 100
            }
          },
          {
            "table": {
              "table_name": "cscart_products_categories",
              "access_type": "ref",
              "possible_keys": ["PRIMARY", "pt"],
              "key": "pt",
              "key_length": "3",
              "used_key_parts": ["product_id"],
              "ref": ["const"],
              "rows": 1,
              "filtered": 100
            }
          },
          {
            "table": {
              "table_name": "cscart_categories",
              "access_type": "eq_ref",
              "possible_keys": ["PRIMARY", "p_category_id"],
              "key": "PRIMARY",
              "key_length": "3",
              "used_key_parts": ["category_id"],
              "ref": ["lillyshop_lillyshop.cscart_products_categories.category_id"],
              "rows": 1,
              "filtered": 100,
              "attached_condition": "cscart_categories.`status` = 'A'"
            }
          }
        ]
      }
    }
  }
}