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 (
    338, 331, 6705, 3932, 3134, 3116, 3126, 
    6673, 6679, 6691, 3155, 3131, 310, 303, 
    3939, 317, 3132, 3143, 3130, 3129, 3121, 
    3128, 6681, 6695, 3098, 3115, 6690, 
    6700, 12, 13, 14, 15, 16, 17, 18, 65, 66, 
    67, 68, 69, 70, 71, 119, 120, 121, 122, 
    123, 124, 125, 126, 127, 128, 129, 130, 
    131, 132, 233, 234, 235, 236, 237, 238, 
    239, 286, 287, 288, 289, 290, 291, 292, 
    3922, 3923, 3924, 3925, 3926, 3927, 
    3928, 3976, 3977, 3978, 3979, 3980, 
    3981, 3982, 4028, 4029, 4030, 4031, 
    4032, 4033, 4034, 4035, 4036, 4037, 
    4038, 4039
  ) 
  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 0.00182

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "67.21"
    },
    "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": 96,
        "rows_produced_per_join": 19,
        "filtered": "19.99",
        "index_condition": "(`test2_gaseus`.`cscart_product_prices`.`product_id` in (338,331,6705,3932,3134,3116,3126,6673,6679,6691,3155,3131,310,303,3939,317,3132,3143,3130,3129,3121,3128,6681,6695,3098,3115,6690,6700,12,13,14,15,16,17,18,65,66,67,68,69,70,71,119,120,121,122,123,124,125,126,127,128,129,130,131,132,233,234,235,236,237,238,239,286,287,288,289,290,291,292,3922,3923,3924,3925,3926,3927,3928,3976,3977,3978,3979,3980,3981,3982,4028,4029,4030,4031,4032,4033,4034,4035,4036,4037,4038,4039))",
        "cost_info": {
          "read_cost": "65.29",
          "eval_cost": "1.92",
          "prefix_cost": "67.21",
          "data_read_per_join": "460"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`test2_gaseus`.`cscart_product_prices`.`lower_limit` = 1) and (`test2_gaseus`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}