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 (
    17, 171996, 121248, 143251, 162699, 
    121501, 177837, 131575, 135087, 155693, 
    137836, 134775, 170928, 172389, 158791, 
    123506, 150952, 160442, 165526, 178218, 
    139924, 125271, 153879, 147591, 170626, 
    164771, 119866, 128957, 146234, 161829, 
    148692, 139499
  ) 
  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 0.02133

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.13249358,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_prices",
          "access_type": "range",
          "possible_keys": [
            "usergroup",
            "product_id",
            "lower_limit",
            "usergroup_id",
            "wdbi_product_id_lower_limit_usergroup_id_price_eff1727beeef",
            "wdbi_usergroup_id_lower_limit_product_id_92b7e8f6a250",
            "wdbi_product_id_lower_limit_usergroup_id_price_perc_3b2301d551d0",
            "wdbi_lower_limit_usergroup_id_product_id_b93629431718"
          ],
          "key": "usergroup",
          "key_length": "9",
          "used_key_parts": ["product_id", "usergroup_id", "lower_limit"],
          "loops": 1,
          "rows": 64,
          "cost": 0.11207368,
          "filtered": 20,
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.product_id in (17,171996,121248,143251,162699,121501,177837,131575,135087,155693,137836,134775,170928,172389,158791,123506,150952,160442,165526,178218,139924,125271,153879,147591,170626,164771,119866,128957,146234,161829,148692,139499) 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": [
            "u985510652_ecartify_abhi.cscart_product_prices.product_id",
            "const"
          ],
          "loops": 12.8,
          "rows": 1,
          "cost": 0.012268032,
          "filtered": 100,
          "attached_condition": "trigcond(cscart_master_products_storefront_min_price.product_id = cscart_product_prices.product_id)"
        }
      }
    ]
  }
}