SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '124a4fa224de30a303aa79e73b41a3cd73ff62572c8345fb49a8b93348f8441e' 
  AND token = '3n2ngWPQtE59nKZOkXf+KeMJHdHhcASupxSWZU8plPk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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