SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fbf503c885bbdb58084baa74533add90fd8edb94d9837010ae8703b44976f42' 
  AND token = '5BhpRluKFLvTEtipjnTb3YA/jY6hxu+1C+2MeJRr3jw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}