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 (
    2187, 2244, 2172, 2171, 1668, 8586, 8372, 
    2222, 2175, 2228, 2220, 2177, 2230, 
    2226, 1667, 2221, 2179, 1666, 8240, 
    2183, 8813, 2176, 8433, 2224, 2195, 
    2225, 8514, 2189, 2196, 2186, 2180, 
    2178, 2191, 2170, 2181, 2190, 2185, 
    2198, 2182, 2188
  ) 
  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 0.00120

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "28.01"
    },
    "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": 40,
        "rows_produced_per_join": 7,
        "filtered": "19.99",
        "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_prices`.`product_id` in (2187,2244,2172,2171,1668,8586,8372,2222,2175,2228,2220,2177,2230,2226,1667,2221,2179,1666,8240,2183,8813,2176,8433,2224,2195,2225,8514,2189,2196,2186,2180,2178,2191,2170,2181,2190,2185,2198,2182,2188))",
        "cost_info": {
          "read_cost": "27.21",
          "eval_cost": "0.80",
          "prefix_cost": "28.01",
          "data_read_per_join": "191"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_prices`.`lower_limit` = 1) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}

Result

product_id price
1666 45000.00000000
1667 44000.00000000
1668 74000.00000000
2170 14000.00000000
2171 18000.00000000
2172 18000.00000000
2175 21000.00000000
2176 21000.00000000
2177 15000.00000000
2178 22000.00000000
2179 29000.00000000
2180 29000.00000000
2181 29000.00000000
2182 29000.00000000
2183 34000.00000000
2185 57000.00000000
2186 53500.00000000
2187 53000.00000000
2188 44000.00000000
2189 29000.00000000
2190 29000.00000000
2191 45500.00000000
2195 43000.00000000
2196 26000.00000000
2198 45500.00000000
2220 110000.00000000
2221 65000.00000000
2222 39000.00000000
2224 18000.00000000
2225 23000.00000000
2226 22000.00000000
2228 19000.00000000
2230 14000.00000000
2244 44000.00000000
8240 24000.00000000
8372 17000.00000000
8433 79000.00000000
8514 29000.00000000
8586 59000.00000000
8813 27000.00000000