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 (
    1452, 1425, 1438, 1424, 1413, 1450, 1469, 
    1455, 1443, 1418, 1634, 1664, 1641, 
    1671, 1627, 1657, 1655, 1686, 1646, 
    1677, 1636, 1666, 1638, 1668, 1644
  ) 
  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 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "20.21"
    },
    "grouping_operation": {
      "using_filesort": false,
      "table": {
        "table_name": "cscart_product_prices",
        "access_type": "range",
        "possible_keys": [
          "usergroup",
          "product_id",
          "lower_limit",
          "usergroup_id"
        ],
        "key": "product_id",
        "used_key_parts": [
          "product_id"
        ],
        "key_length": "3",
        "rows_examined_per_scan": 31,
        "rows_produced_per_join": 6,
        "filtered": "19.99",
        "index_condition": "(`cscartdevel`.`cscart_product_prices`.`product_id` in (1452,1425,1438,1424,1413,1450,1469,1455,1443,1418,1634,1664,1641,1671,1627,1657,1655,1686,1646,1677,1636,1666,1638,1668,1644))",
        "cost_info": {
          "read_cost": "19.59",
          "eval_cost": "0.62",
          "prefix_cost": "20.21",
          "data_read_per_join": "148"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`cscartdevel`.`cscart_product_prices`.`lower_limit` = 1) and (`cscartdevel`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}