SELECT 
  q_product_prices.product_id, 
  MIN(
    IF(
      q_product_prices.percentage_discount = 0, 
      q_product_prices.price, 
      q_product_prices.price - (
        q_product_prices.price * q_product_prices.percentage_discount
      )/ 100
    )
  ) AS price 
FROM 
  q_product_prices 
WHERE 
  q_product_prices.product_id IN (
    1593, 1594, 1595, 1596, 1597, 1598, 1599, 
    1600, 1601, 1602, 1603, 1605, 1606, 
    1607, 1610, 1611, 1612, 1613, 1614, 
    1615, 1616, 1617, 1618, 1624, 1625, 
    1626, 1627, 1628
  ) 
  AND q_product_prices.lower_limit = 1 
  AND q_product_prices.usergroup_id IN (0, 1) 
GROUP BY 
  q_product_prices.product_id

Query time 0.00096

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "67.21"
    },
    "grouping_operation": {
      "using_filesort": false,
      "table": {
        "table_name": "q_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": 28,
        "rows_produced_per_join": 5,
        "filtered": "19.99",
        "index_condition": "(`portal`.`q_product_prices`.`product_id` in (1593,1594,1595,1596,1597,1598,1599,1600,1601,1602,1603,1605,1606,1607,1610,1611,1612,1613,1614,1615,1616,1617,1618,1624,1625,1626,1627,1628))",
        "cost_info": {
          "read_cost": "66.09",
          "eval_cost": "1.12",
          "prefix_cost": "67.21",
          "data_read_per_join": "134"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`portal`.`q_product_prices`.`lower_limit` = 1) and (`portal`.`q_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}