At the very beginning of the movie, when all the stores around New York are opening, several stores have metal bars in front of them that are being unlocked, raised, opened, etc. One of these stores has a sign in the window that says "Open 24 hours". Why would a store that's open 24 hours be closed?
The sign behind the bars does not say "open 24 hours." It says "24 hour service." It has a phone number directly below the phrase. It does not say, in any form or fashion, that the actual physical store is open 24 hours.
If you have a DVD, you can find this in chapter 3. It does have a neon key shape that says "24 hr ser" in the window because it's a locksmith shop. They usually are a 24-hour on-call service.