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 (
    2734, 2735, 2694, 2695, 2696, 2697, 2698, 
    2699, 2700, 2701, 2675, 2676, 2677, 
    2678, 2679, 2680, 2681, 2682, 2683, 
    2684, 2685, 2686, 2687, 2688, 2689, 
    2607, 2608, 2609, 2610, 2611
  ) 
  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 0.00102

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "72.01"
    },
    "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": 30,
        "rows_produced_per_join": 5,
        "filtered": "19.99",
        "index_condition": "(`portal`.`q_product_prices`.`product_id` in (2734,2735,2694,2695,2696,2697,2698,2699,2700,2701,2675,2676,2677,2678,2679,2680,2681,2682,2683,2684,2685,2686,2687,2688,2689,2607,2608,2609,2610,2611))",
        "cost_info": {
          "read_cost": "70.81",
          "eval_cost": "1.20",
          "prefix_cost": "72.01",
          "data_read_per_join": "143"
        },
        "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)))"
      }
    }
  }
}