SELECT 
  cscart_ult_product_prices.product_id, 
  MIN(
    IF(
      cscart_ult_product_prices.percentage_discount = 0, 
      cscart_ult_product_prices.price, 
      cscart_ult_product_prices.price - (
        cscart_ult_product_prices.price * cscart_ult_product_prices.percentage_discount
      )/ 100
    )
  ) AS price 
FROM 
  cscart_ult_product_prices 
WHERE 
  cscart_ult_product_prices.product_id IN (
    5531, 5528, 5525, 5521, 5526, 5515, 5501, 
    5529, 5503, 5512, 5514, 5511, 5523, 
    5513, 5516, 5524, 5518, 5527, 5519, 
    5532, 5530, 5517, 6766, 6730
  ) 
  AND cscart_ult_product_prices.lower_limit = 1 
  AND cscart_ult_product_prices.company_id = 1 
  AND cscart_ult_product_prices.usergroup_id IN (0, 0, 1) 
GROUP BY 
  cscart_ult_product_prices.product_id

Query time 0.00060

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "sort_key": "cscart_ult_product_prices.product_id",
      "temporary_table": {
        "table": {
          "table_name": "cscart_ult_product_prices",
          "access_type": "ALL",
          "possible_keys": [
            "usergroup",
            "product_id",
            "company_id",
            "lower_limit",
            "usergroup_id"
          ],
          "rows": 44,
          "filtered": 54.54545593,
          "attached_condition": "cscart_ult_product_prices.lower_limit = 1 and cscart_ult_product_prices.company_id = 1 and cscart_ult_product_prices.product_id in (5531,5528,5525,5521,5526,5515,5501,5529,5503,5512,5514,5511,5523,5513,5516,5524,5518,5527,5519,5532,5530,5517,6766,6730) and cscart_ult_product_prices.usergroup_id in (0,0,1)"
        }
      }
    }
  }
}