Should I use scopes if I only have one endpoint?

Not really today, and that's a fine answer. Scopes earn their keep the moment you have a second thing the key could do and you want one caller to only do the first.

What I'd say is: leave the scope check in your call now even if the key has every scope. Adding the parameter later, across a codebase, is the annoying part. Passing it when it always passes costs nothing.