SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd51098ed3d0d83963d5a6928b8e671bbad9b7eb07e1e61d37ea88e81458f1a7' 
  AND token = 'vAHlHkYBJK+A4gsBZ6FhzzrDDdWfZV9ulX80RXxwlFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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