SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5503f03d0f83aa85ecd6a408be86d970348b666e05d52c236de6d22a25631003' 
  AND token = 'pH+5+JmqA9B75pglj+RJ1zalf6gQMhWhwHM003KX80k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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