SELECT 
  addon 
FROM 
  cscart_addons 
WHERE 
  unmanaged = 1 
  AND status = 'A' 
ORDER BY 
  priority

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "ordering_operation": {
      "using_filesort": true,
      "table": {
        "table_name": "cscart_addons",
        "access_type": "ALL",
        "rows": 24,
        "filtered": 100,
        "attached_condition": "((`_testcscart`.`cscart_addons`.`unmanaged` = 1) and (`_testcscart`.`cscart_addons`.`status` = 'A'))"
      }
    }
  }
}