SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8df31b9493b59e4a893fc6ef54792e798c74c897ef9f6f1b7d807212bea4ff20' 
  AND token = '5KTwP0AjyNmh0v6Zu23iMF8pHLPnJqYIl5q/3eI1n40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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