SELECT 
  tax_id, 
  address_type, 
  priority, 
  price_includes_tax, 
  regnumber 
FROM 
  cscart_taxes 
WHERE 
  tax_id IN (7, 8, 9) 
  AND status = 'A' 
ORDER BY 
  priority

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "read_sorted_file": {
      "filesort": {
        "sort_key": "cscart_taxes.priority",
        "table": {
          "table_name": "cscart_taxes",
          "access_type": "ALL",
          "possible_keys": ["PRIMARY"],
          "rows": 3,
          "filtered": 100,
          "attached_condition": "cscart_taxes.tax_id in (7,8,9) and cscart_taxes.`status` = 'A'"
        }
      }
    }
  }
}