SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '424deb565a22d17dbcec99969a818ffab0f0d8725b9314a1cea0203825aaf6e0' 
  AND token = 'KzFte4YNECKJxBhQhMx7OeOjnEMQmuFvt+DjUGsJbNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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