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 (
    1078, 886, 884, 679, 1100, 1103, 603, 
    601, 887, 885, 609, 596, 599, 605, 1094, 
    1093, 1075, 892, 922, 880, 908, 909, 
    910, 900, 672, 896, 882, 902, 926, 895, 
    936, 598, 934, 937, 894, 913, 889, 890, 
    888, 932, 933, 675, 911, 914, 924, 920, 
    918
  ) 
  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 0.00080

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "191.16"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "94.00"
      },
      "table": {
        "table_name": "cscart_product_prices",
        "access_type": "ALL",
        "possible_keys": [
          "usergroup",
          "product_id",
          "lower_limit",
          "usergroup_id"
        ],
        "rows_examined_per_scan": 465,
        "rows_produced_per_join": 94,
        "filtered": "20.22",
        "cost_info": {
          "read_cost": "78.36",
          "eval_cost": "18.80",
          "prefix_cost": "97.16",
          "data_read_per_join": "2K"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`cscart`.`cscart_product_prices`.`lower_limit` = 1) and (`cscart`.`cscart_product_prices`.`product_id` in (1078,886,884,679,1100,1103,603,601,887,885,609,596,599,605,1094,1093,1075,892,922,880,908,909,910,900,672,896,882,902,926,895,936,598,934,937,894,913,889,890,888,932,933,675,911,914,924,920,918)) and (`cscart`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}