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 (
    6945, 6947, 6948, 6959, 6971, 6975, 7019, 
    7060, 7062, 7064, 7065, 7094, 7107, 
    7109, 7122, 7136, 7140, 7158, 7161, 
    7204, 7206, 7209, 7297, 6966, 6846, 
    6873, 6883, 6896, 6907, 6908, 6909, 
    6914, 6927, 6950, 6955, 6956, 6963, 
    7003, 7061, 7104, 7164, 7165, 7179, 
    7181, 7273, 7275, 7305, 7310, 7311, 
    6897, 7106, 6967, 6898, 6901, 6915, 
    6932, 6964, 6969, 7090, 7108, 7201, 
    7203, 7207, 7301, 7312, 6890, 6894, 
    6910, 6919, 6974, 6998, 7114, 7298, 
    7327, 7143, 7309, 7314, 7063
  ) 
  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 0.00186

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "54.61"
    },
    "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": 78,
        "rows_produced_per_join": 15,
        "filtered": "19.99",
        "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_prices`.`product_id` in (6945,6947,6948,6959,6971,6975,7019,7060,7062,7064,7065,7094,7107,7109,7122,7136,7140,7158,7161,7204,7206,7209,7297,6966,6846,6873,6883,6896,6907,6908,6909,6914,6927,6950,6955,6956,6963,7003,7061,7104,7164,7165,7179,7181,7273,7275,7305,7310,7311,6897,7106,6967,6898,6901,6915,6932,6964,6969,7090,7108,7201,7203,7207,7301,7312,6890,6894,6910,6919,6974,6998,7114,7298,7327,7143,7309,7314,7063))",
        "cost_info": {
          "read_cost": "53.05",
          "eval_cost": "1.56",
          "prefix_cost": "54.61",
          "data_read_per_join": "374"
        },
        "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)))"
      }
    }
  }
}