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 (
    3818, 3819, 3820, 3821, 3822, 3823, 3824, 
    3825, 3826, 3827, 3828, 3829, 3830, 
    3831, 3832, 3778, 2103, 2104, 2105, 
    2106, 2107, 2108, 2109, 2110, 2111, 
    2112, 2113, 2114, 2115, 2116, 2117, 
    2118, 2119, 2120, 2121, 2122, 2123, 
    2124, 2125, 2126, 2127, 2128, 2129, 
    3752, 3753, 3754, 3755, 3756, 3757, 
    3758, 3759, 3760, 3761, 3762, 3763, 
    3764, 3765, 3766, 3767, 3768, 3769, 
    3770, 3771, 3772, 3773, 3774, 3775, 
    3776, 3777, 1143, 1139, 1140, 1141, 
    1142, 3681, 3682, 3683, 3684, 3685, 
    4890, 2207, 2208, 2209, 2210, 2211, 
    2212, 2213, 2214, 2215, 2216, 5808, 
    5809, 5810, 5811, 5812, 5813
  ) 
  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 0.00177

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 (3818,3819,3820,3821,3822,3823,3824,3825,3826,3827,3828,3829,3830,3831,3832,3778,2103,2104,2105,2106,2107,2108,2109,2110,2111,2112,2113,2114,2115,2116,2117,2118,2119,2120,2121,2122,2123,2124,2125,2126,2127,2128,2129,3752,3753,3754,3755,3756,3757,3758,3759,3760,3761,3762,3763,3764,3765,3766,3767,3768,3769,3770,3771,3772,3773,3774,3775,3776,3777,1143,1139,1140,1141,1142,3681,3682,3683,3684,3685,4890,2207,2208,2209,2210,2211,2212,2213,2214,2215,2216,5808,5809,5810,5811,5812,5813))",
        "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)))"
      }
    }
  }
}