SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c39614b40a65e7f9e966c4f529125257721eb4fe63f86f8847633290f9402b86' 
  AND token = 'jLpzUuZB5dhVdQjOWfFveAbq8iAcOg7iiFFlxz2ennU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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