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 (
    41308, 41309, 41310, 41311, 41312, 41313, 
    41314, 41315, 41317, 41318, 41319, 
    41320, 41321, 41322, 41323, 41324, 
    41325, 41326, 41327, 41328, 41329, 
    41330, 41331, 41332, 41333, 41334, 
    41335, 41336, 41337, 41338
  ) 
  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 0.00093

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "102.81"
    },
    "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": 52,
        "rows_produced_per_join": 10,
        "filtered": "19.99",
        "index_condition": "(`portal`.`q_product_prices`.`product_id` in (41308,41309,41310,41311,41312,41313,41314,41315,41317,41318,41319,41320,41321,41322,41323,41324,41325,41326,41327,41328,41329,41330,41331,41332,41333,41334,41335,41336,41337,41338))",
        "cost_info": {
          "read_cost": "100.73",
          "eval_cost": "2.08",
          "prefix_cost": "102.81",
          "data_read_per_join": "249"
        },
        "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)))"
      }
    }
  }
}