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 (
    32721, 32722, 32723, 32724, 32725, 32726, 
    32727, 32728, 32729, 32730, 32731, 
    32732, 32733, 32734, 32735, 32736, 
    32737, 32738, 32739, 32740, 32741, 
    32742, 32743, 32744, 32745, 32746, 
    32747, 32748, 32749, 32750, 32751, 
    32752
  ) 
  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 0.00084

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "78.21"
    },
    "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": 33,
        "rows_produced_per_join": 6,
        "filtered": "19.99",
        "index_condition": "(`portal`.`q_product_prices`.`product_id` in (32721,32722,32723,32724,32725,32726,32727,32728,32729,32730,32731,32732,32733,32734,32735,32736,32737,32738,32739,32740,32741,32742,32743,32744,32745,32746,32747,32748,32749,32750,32751,32752))",
        "cost_info": {
          "read_cost": "76.89",
          "eval_cost": "1.32",
          "prefix_cost": "78.21",
          "data_read_per_join": "158"
        },
        "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)))"
      }
    }
  }
}