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 (
    1868, 1869, 1870, 1871, 1872, 1874, 1875, 
    1876, 1877, 3748, 3749, 3750, 3751, 
    5505, 5506, 5507, 5508, 5509, 5510, 
    5511, 5512, 5513, 5514, 5515, 5516, 
    5517, 5518, 5519, 5520, 5521, 5522, 
    5523, 5524, 5525, 5526, 5527, 5528, 
    5529, 5530, 5531, 5532, 5533, 5534, 
    5535, 5536, 5537, 5538, 5539, 5540, 
    5541, 5542, 5543, 5544, 5545, 5546, 
    5547, 5548, 5549, 5550, 5551, 5552, 
    5553, 5554, 5555, 5556, 5557, 5558, 
    5559, 1457, 5166, 1447, 5156, 5169, 
    3162, 1450, 5159, 1440, 5149, 1451, 
    5160, 1441, 5150, 1453, 5162, 1443, 
    5152, 1770, 1771, 1772, 1773, 1774, 
    1775, 1776, 1777, 1778, 1779
  ) 
  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 0.00208

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 (1868,1869,1870,1871,1872,1874,1875,1876,1877,3748,3749,3750,3751,5505,5506,5507,5508,5509,5510,5511,5512,5513,5514,5515,5516,5517,5518,5519,5520,5521,5522,5523,5524,5525,5526,5527,5528,5529,5530,5531,5532,5533,5534,5535,5536,5537,5538,5539,5540,5541,5542,5543,5544,5545,5546,5547,5548,5549,5550,5551,5552,5553,5554,5555,5556,5557,5558,5559,1457,5166,1447,5156,5169,3162,1450,5159,1440,5149,1451,5160,1441,5150,1453,5162,1443,5152,1770,1771,1772,1773,1774,1775,1776,1777,1778,1779))",
        "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)))"
      }
    }
  }
}