I was sick when the news about php2shell broke, so ended up leaving two of my personal sites that use php un-patched for about 48 hours until my fever broke and I patched them. I didn’t get hacked. Was I just lucky and so shouldn’t infer anything about how hard it is to actually make use of this vulnerability? Probably.
Another theory is your server got compromised but they cleared their tracks. Not every hacker wants to make a quick few cents from a miner that gets shut down in a day or two.