SELECT 
  cscart_product_prices.product_id, 
  MIN(
    IF(
      cscart_product_prices.percentage_discount = 0, 
      cscart_product_prices.price, 
      cscart_product_prices.price - (
        cscart_product_prices.price * cscart_product_prices.percentage_discount
      )/ 100
    )
  ) AS price 
FROM 
  cscart_product_prices 
WHERE 
  cscart_product_prices.product_id IN (
    7580, 8152, 8156, 7655, 7633, 7622, 8075, 
    10686, 8171, 8292, 10739, 10741, 8747, 
    10624, 8161, 10694, 7653, 8176, 8178, 
    8383, 8207, 11086, 11114, 8127
  ) 
  AND cscart_product_prices.lower_limit = 1 
  AND cscart_product_prices.usergroup_id IN (0, 1) 
GROUP BY 
  cscart_product_prices.product_id

Query time 0.01312

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "sort_key": "cscart_product_prices.product_id",
      "temporary_table": {
        "nested_loop": [
          {
            "table": {
              "table_name": "cscart_product_prices",
              "access_type": "ref",
              "possible_keys": [
                "usergroup",
                "product_id",
                "lower_limit",
                "usergroup_id"
              ],
              "key": "lower_limit",
              "key_length": "3",
              "used_key_parts": ["lower_limit"],
              "ref": ["const"],
              "rows": 11706,
              "filtered": 9.840266228,
              "attached_condition": "cscart_product_prices.lower_limit <=> 1 and cscart_product_prices.product_id in (7580,8152,8156,7655,7633,7622,8075,10686,8171,8292,10739,10741,8747,10624,8161,10694,7653,8176,8178,8383,8207,11086,11114,8127) and cscart_product_prices.usergroup_id in (0,1)"
            }
          }
        ]
      }
    }
  }
}