@amitsolanki24_ i still dont get it, here is an example of signed url:
http://example.com/dashboard?user=1&signature=1235c56df4c8ad3228593860f5e26466847249752b30f18540634707f23
if the user changes the signature parameter, it leads to 403, because the signature is altered, thus invalid. the url exists (http://example.com/dashboard), the signature is never stored, it is just an encrypted string with parameters. that is why you cannot check whether it exists or not.
i mean, you could if you wanted. to store all of generated signed urls and then compare them in a middleware or something, but i personally dont see a point of that. and you probably also disclose information about the signature existence/absence, which might not be a big deal, but the less to disclose, the better.