SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '731780c2a79ee9ed6caa7ec3d326e0a88e3125d1e8a551a56f8854daa7ad934c' 
  AND token = 'gJGXqsbR7ruf78ys91/G8UdJ4rmFIIQAqqsXEkuQ5Ng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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