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

Query time 0.00094

JSON explain

{
  "query_block": {
    "select_id": 1,
    "read_sorted_file": {
      "filesort": {
        "sort_key": "cscart_addons.priority",
        "table": {
          "table_name": "cscart_addons",
          "access_type": "ALL",
          "rows": 81,
          "filtered": 100,
          "attached_condition": "cscart_addons.unmanaged = 1 and cscart_addons.`status` = 'A'"
        }
      }
    }
  }
}