SELECT 
  tmall_product_prices.product_id, 
  COALESCE(
    tmall_master_products_storefront_min_price.price, 
    MIN(
      IF(
        tmall_product_prices.percentage_discount = 0, 
        tmall_product_prices.price, 
        tmall_product_prices.price - (
          tmall_product_prices.price * tmall_product_prices.percentage_discount
        )/ 100
      )
    )
  ) AS price 
FROM 
  tmall_product_prices 
  LEFT JOIN tmall_master_products_storefront_min_price ON tmall_master_products_storefront_min_price.product_id = tmall_product_prices.product_id 
  AND tmall_master_products_storefront_min_price.storefront_id = 1 
WHERE 
  tmall_product_prices.product_id IN (
    114, 108, 104, 121, 103, 112, 97, 116, 
    111, 110, 118, 123, 119, 100
  ) 
  AND tmall_product_prices.lower_limit = 1 
  AND tmall_product_prices.usergroup_id IN (0, 1) 
GROUP BY 
  tmall_product_prices.product_id

Query time 0.00772

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.034909764,
    "nested_loop": [
      {
        "table": {
          "table_name": "tmall_master_products_storefront_min_price",
          "access_type": "system",
          "possible_keys": ["PRIMARY"],
          "rows": 0,
          "filtered": 0,
          "const_row_not_found": true
        }
      },
      {
        "table": {
          "table_name": "tmall_product_prices",
          "access_type": "range",
          "possible_keys": [
            "usergroup",
            "product_id",
            "lower_limit",
            "usergroup_id"
          ],
          "key": "product_id",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "loops": 1,
          "rows": 14,
          "cost": 0.026229496,
          "filtered": 97.28681946,
          "index_condition": "tmall_product_prices.product_id in (114,108,104,121,103,112,97,116,111,110,118,123,119,100)",
          "attached_condition": "tmall_product_prices.lower_limit = 1 and tmall_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}