SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '0bbd753dcae536773cf907c096ad30d98e0218fb5a43f48bf7bf8f3d6913849c' 
  AND token = 'U++MT+/VDbdcko7aW6jPOlAwte9sPwYKIXXWIGApCjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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