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 (
    29707, 29709, 29712, 29716, 29718, 29726, 
    29727, 29728, 29732, 29733, 29735, 
    29736, 29737, 29743, 29747, 29748, 
    29754, 29755, 29758, 29761, 29762, 
    29765, 29766, 29769, 29770, 29771, 
    29775, 29780, 29781, 29787
  ) 
  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 0.00089

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "86.01"
    },
    "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": 40,
        "rows_produced_per_join": 7,
        "filtered": "19.99",
        "index_condition": "(`portal`.`q_product_prices`.`product_id` in (29707,29709,29712,29716,29718,29726,29727,29728,29732,29733,29735,29736,29737,29743,29747,29748,29754,29755,29758,29761,29762,29765,29766,29769,29770,29771,29775,29780,29781,29787))",
        "cost_info": {
          "read_cost": "84.41",
          "eval_cost": "1.60",
          "prefix_cost": "86.01",
          "data_read_per_join": "191"
        },
        "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)))"
      }
    }
  }
}