SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    298, 232, 54, 337, 5473, 315, 236, 3478, 
    341, 5475, 59, 309, 65, 69, 70, 75, 5556, 
    76
  )

Query time 0.00068

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 18,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (298,232,54,337,5473,315,236,3478,341,5475,59,309,65,69,70,75,5556,76)"
    }
  }
}