もっと他のやり方がありそうなんだけど一応

const KEY_QUERY_VALUE = &H0001
const HKEY_CURRENT_USER = &H80000001
const HKEY_LOCAL_MACHINE = &H80000002
Set objReg=GetObject("winmgmts:{impersonationLevel=impersonate}!\\.\root\default:StdRegProv")
strKeyPath = "SOFTWARE\developer\app\key"
Result = objReg.CheckAccess(HKEY_CURRENT_USER, strKeyPath, KEY_QUERY_VALUE, bHasAccessRight)
If Result = 0 Then
Wscript.Echo "key found."
ElseIf Result = 2 Then ' WBEM_E_NOT_FOUND
Wscript.Echo "key not found."
Else
Wscript.Echo "other error."
End If