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 (
    34239, 34249, 34250, 34262, 34349, 34469, 
    34487, 34538, 2464, 2465, 2466, 2467, 
    2469, 1175, 1176, 1177, 1178, 1179, 
    1180, 1181, 1182, 1183, 1184, 1191, 
    1011, 1010, 1009, 999, 998, 997, 975, 
    958
  ) 
  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 0.00108

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "85.21"
    },
    "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": 38,
        "rows_produced_per_join": 7,
        "filtered": "19.99",
        "index_condition": "(`portal`.`q_product_prices`.`product_id` in (34239,34249,34250,34262,34349,34469,34487,34538,2464,2465,2466,2467,2469,1175,1176,1177,1178,1179,1180,1181,1182,1183,1184,1191,1011,1010,1009,999,998,997,975,958))",
        "cost_info": {
          "read_cost": "83.69",
          "eval_cost": "1.52",
          "prefix_cost": "85.21",
          "data_read_per_join": "182"
        },
        "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)))"
      }
    }
  }
}