SELECT 
  * 
FROM 
  cscart_abt__ut2_fly_menu_content 
WHERE 
  storefront_id = 1 
ORDER BY 
  position asc

Query time 0.00012

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.017247243,
    "nested_loop": [
      {
        "read_sorted_file": {
          "filesort": {
            "sort_key": "cscart_abt__ut2_fly_menu_content.position",
            "table": {
              "table_name": "cscart_abt__ut2_fly_menu_content",
              "access_type": "ALL",
              "loops": 1,
              "rows": 8,
              "cost": 0.0121588,
              "filtered": 100,
              "attached_condition": "cscart_abt__ut2_fly_menu_content.storefront_id = 1"
            }
          }
        }
      }
    ]
  }
}