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 (
    32881, 32882, 32883, 32884, 32885, 32886, 
    32887, 32888, 32889, 32890, 32891, 
    10533, 10532, 10531, 10530, 10529, 
    10524, 10521, 8380, 8381, 8383, 8384, 
    8385, 8386, 8387, 8388, 8389, 8390, 
    8391, 8392, 8393, 8394
  ) 
  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 0.00088

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "96.41"
    },
    "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": 46,
        "rows_produced_per_join": 9,
        "filtered": "19.99",
        "index_condition": "(`portal`.`q_product_prices`.`product_id` in (32881,32882,32883,32884,32885,32886,32887,32888,32889,32890,32891,10533,10532,10531,10530,10529,10524,10521,8380,8381,8383,8384,8385,8386,8387,8388,8389,8390,8391,8392,8393,8394))",
        "cost_info": {
          "read_cost": "94.57",
          "eval_cost": "1.84",
          "prefix_cost": "96.41",
          "data_read_per_join": "220"
        },
        "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)))"
      }
    }
  }
}