Hi David
Apple Watch does not have built-in GPS features, so cannot be physically located in the same way as, for example, an iPhone (using Find My iPhone).
As the support article for Activation Lock explains, rather than unpairing your watch from your iPhone, you should instead have turned on Mark as Missing. This feature disables Apple Pay cards on your watch and also keeps Activation Lock enabled on your watch. This prevents anyone else from pairing it to their own iPhone without knowing your Apple ID and password.
More information:
About Activation Lock on Apple Watch - Apple Support