Please help!

I’m starting to freak out a little and need advice. I had unprotected sex last night, maybe less than 60 seconds without a condom before I stopped and said to get a condom. Nothing happened but still there is that thought that makes me freak out. I have a plan b pill but don’t know if I should take it?? I have like 2 days to decide if I want to take it or not. I’ve recently started having sex so this is why I’m so unsure of what to do. Please help!