SELECT 
  cscart_product_prices.product_id, 
  MIN(
    IF(
      cscart_product_prices.percentage_discount = 0, 
      cscart_product_prices.price, 
      cscart_product_prices.price - (
        cscart_product_prices.price * cscart_product_prices.percentage_discount
      )/ 100
    )
  ) AS price 
FROM 
  cscart_product_prices 
WHERE 
  cscart_product_prices.product_id IN (
    1615, 1616, 1617, 1618, 1619, 1620, 1621, 
    1622, 1623, 1624, 1625, 5299, 5300, 
    5301, 5302, 5303, 5304, 5305, 5306, 
    5307, 5308, 5309, 5310, 5311, 5312, 
    5313, 5314, 5315, 5316, 5317, 5318, 
    5319, 5320, 5321, 5322, 5323, 5324, 
    5325, 1627, 1628, 1629, 1630, 1631, 
    1632, 1633, 1634, 1635, 1636, 1637, 
    1638, 1639, 1640, 1641, 1642, 1643, 
    1644, 1645, 1646, 1647, 1648, 1649, 
    1650, 1651, 1652, 5326, 5327, 5328, 
    5329, 5330, 5331, 5332, 5333, 5334, 
    5335, 5336, 5337, 5338, 5339, 5340, 
    5341, 5342, 5343, 5344, 5345, 5346, 
    5347, 5348, 5349, 5350, 5351, 5352, 
    2832, 2833, 2834, 2835, 6417
  ) 
  AND cscart_product_prices.lower_limit = 1 
  AND cscart_product_prices.usergroup_id IN (0, 1) 
GROUP BY 
  cscart_product_prices.product_id

Query time 0.00144

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "67.66"
    },
    "grouping_operation": {
      "using_filesort": false,
      "table": {
        "table_name": "cscart_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": 97,
        "rows_produced_per_join": 19,
        "filtered": "20.00",
        "index_condition": "(`gaseus`.`cscart_product_prices`.`product_id` in (1615,1616,1617,1618,1619,1620,1621,1622,1623,1624,1625,5299,5300,5301,5302,5303,5304,5305,5306,5307,5308,5309,5310,5311,5312,5313,5314,5315,5316,5317,5318,5319,5320,5321,5322,5323,5324,5325,1627,1628,1629,1630,1631,1632,1633,1634,1635,1636,1637,1638,1639,1640,1641,1642,1643,1644,1645,1646,1647,1648,1649,1650,1651,1652,5326,5327,5328,5329,5330,5331,5332,5333,5334,5335,5336,5337,5338,5339,5340,5341,5342,5343,5344,5345,5346,5347,5348,5349,5350,5351,5352,2832,2833,2834,2835,6417))",
        "cost_info": {
          "read_cost": "65.72",
          "eval_cost": "1.94",
          "prefix_cost": "67.66",
          "data_read_per_join": "465"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`gaseus`.`cscart_product_prices`.`lower_limit` = 1) and (`gaseus`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}