Those ^ work well, even on some strap lock-style buttons. I've had one for years — they do get a little untidy at the back where there's a rubberized compound which
can get scored but will save scratches never-the-less. Over time they may break down but so far so good, for me. Don't use it much.
Old school schallers are still utilized by many. All mine — I have a good number — are still going strong and, with minimal maintenance, they never fail. All one needs to do is nip them up and keep them clean. The newer ones look good but I balk at them. To me, because I'm used to the old ones, they seem over-complicated.
I have a number of others — none of them in service. Dunlop, Daddario — who has a number of innovations — some very simple, like this type …
… seem solid (still largely untested by me); others that work like free-floating versions of
the one above don't pass muster — I'm fussy

— but they may be enough, in some situations. If you're going to do things like sling your axe behind you and sing, or go for a wander, or play another instrument with your axe behind your back, steer clear.
I got one recently that's
built like a tank. Haven't had the desire, or the need, to use it. It'd be fine, I imagine, if its bulk suited the application. They are heavy

And there are a good number of other straps out there with locks incorporated into them, like [This invalid link has been removed]. More options, every time I take a look.
I have too many Grolsch washers — they're good but I balk at them too as I can still pull a strap and a washer away from a button without much effort. Sedate players need not worry.
Anything that locks fast is a contender, in my book. The Loxx variety may be my next adventure. They're new to me. The screw shaft diameter cops some flack — too thick — but I don't see that as a problem, as long as you're fully committed. They look pretty good, in general. Dunlops are fine too as they're solid.
Watch out for any knock-offs — they can be cheap and nasty sometimes. Straplocks for me though, as a rule — that's my briar patch — I like to take straps off all the time, and I like to keep them on too, in the interim — going hands-free for any number of reasons. And when you get it all together with Schallers — not so simple but not too difficult either — they do work really well. Off in a shot
and bullet proof.