SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8dc83ac9a90153c53cef797f0e56054fbde8e2fa19211139d84b4f6ec7c16c7' 
  AND token = 'xXUxmuWu6JbfCcihK8v+93TPQeqBVoymrIKliE+wXJ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}