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 (
    29252, 29290, 29292, 29321, 29344, 29351, 
    29352, 29385, 29387, 29388, 29391, 
    29394, 29682, 29685, 29687, 29692, 
    29704, 29707, 29709, 29712, 29718, 
    29732, 29733, 29735, 29736, 29737, 
    29747, 29748, 29754, 29766
  ) 
  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": "81.81"
    },
    "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": 37,
        "rows_produced_per_join": 7,
        "filtered": "19.99",
        "index_condition": "(`portal`.`q_product_prices`.`product_id` in (29252,29290,29292,29321,29344,29351,29352,29385,29387,29388,29391,29394,29682,29685,29687,29692,29704,29707,29709,29712,29718,29732,29733,29735,29736,29737,29747,29748,29754,29766))",
        "cost_info": {
          "read_cost": "80.33",
          "eval_cost": "1.48",
          "prefix_cost": "81.81",
          "data_read_per_join": "177"
        },
        "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)))"
      }
    }
  }
}