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 (
    3741, 3742, 3743, 3744, 3745, 3746, 3747, 
    3748, 3749, 3750, 3751, 3752, 3753, 
    3755, 3756, 3757, 3758, 3759, 3760, 
    3761, 3762, 3764, 3765, 3768, 3769, 
    3772, 1470
  ) 
  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 0.00075

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "64.81"
    },
    "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": 27,
        "rows_produced_per_join": 5,
        "filtered": "19.99",
        "index_condition": "(`portal`.`q_product_prices`.`product_id` in (3741,3742,3743,3744,3745,3746,3747,3748,3749,3750,3751,3752,3753,3755,3756,3757,3758,3759,3760,3761,3762,3764,3765,3768,3769,3772,1470))",
        "cost_info": {
          "read_cost": "63.73",
          "eval_cost": "1.08",
          "prefix_cost": "64.81",
          "data_read_per_join": "129"
        },
        "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)))"
      }
    }
  }
}