SELECT 
  cscart_product_prices.product_id, 
  COALESCE(
    cscart_master_products_storefront_min_price.price, 
    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 
  LEFT JOIN cscart_master_products_storefront_min_price ON cscart_master_products_storefront_min_price.product_id = cscart_product_prices.product_id 
  AND cscart_master_products_storefront_min_price.storefront_id = 1 
WHERE 
  cscart_product_prices.product_id IN (
    99, 97, 98, 91, 96, 182, 451, 454, 453, 
    457, 701, 702, 708, 228, 452, 447, 829, 
    769, 831, 818, 847, 774, 833, 368, 432, 
    433, 434, 435, 436, 437, 438, 439, 440, 
    441, 442, 443, 444, 445, 446, 369, 417, 
    418, 419, 420, 421, 422, 423, 424, 425, 
    426, 427, 428, 429, 430, 431, 367, 402, 
    403, 404, 405, 406, 407, 408, 409, 410, 
    411, 412, 413, 414, 415, 416
  ) 
  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 0.00112

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.155978554,
    "filesort": {
      "sort_key": "cscart_product_prices.product_id",
      "temporary_table": {
        "nested_loop": [
          {
            "table": {
              "table_name": "cscart_product_prices",
              "access_type": "ALL",
              "possible_keys": [
                "usergroup",
                "product_id",
                "lower_limit",
                "usergroup_id"
              ],
              "loops": 1,
              "rows": 473,
              "cost": 0.0896634,
              "filtered": 9.01268959,
              "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.product_id in (99,97,98,91,96,182,451,454,453,457,701,702,708,228,452,447,829,769,831,818,847,774,833,368,432,433,434,435,436,437,438,439,440,441,442,443,444,445,446,369,417,418,419,420,421,422,423,424,425,426,427,428,429,430,431,367,402,403,404,405,406,407,408,409,410,411,412,413,414,415,416) and cscart_product_prices.usergroup_id in (0,1)"
            }
          },
          {
            "table": {
              "table_name": "cscart_master_products_storefront_min_price",
              "access_type": "eq_ref",
              "possible_keys": ["PRIMARY"],
              "key": "PRIMARY",
              "key_length": "8",
              "used_key_parts": ["product_id", "storefront_id"],
              "ref": [
                "u428615623_ecartifygonje.cscart_product_prices.product_id",
                "const"
              ],
              "loops": 42.63002114,
              "rows": 1,
              "cost": 0.038949196,
              "filtered": 100,
              "attached_condition": "trigcond(cscart_master_products_storefront_min_price.product_id = cscart_product_prices.product_id)"
            }
          }
        ]
      }
    }
  }
}