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 (
    187, 232, 230, 231, 170, 131, 177, 186, 
    185, 179, 233, 152, 160, 237, 235, 122, 
    115, 129, 127, 188, 124, 236, 234, 150, 
    151, 181
  ) 
  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 0.00092

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "sort_key": "cscart_ult_product_prices.product_id",
      "temporary_table": {
        "nested_loop": [
          {
            "table": {
              "table_name": "cscart_ult_product_prices",
              "access_type": "ALL",
              "possible_keys": [
                "usergroup",
                "product_id",
                "company_id",
                "lower_limit",
                "usergroup_id"
              ],
              "rows": 4,
              "filtered": 100,
              "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 (187,232,230,231,170,131,177,186,185,179,233,152,160,237,235,122,115,129,127,188,124,236,234,150,151,181) and cscart_ult_product_prices.usergroup_id in (0,0,1)"
            }
          }
        ]
      }
    }
  }
}