Student or Learner
Letīs stop talking. Our boss CAN open the door any time.
Is it right to use CAN in the sentence above, to convey possibility in the future?
Yes, that sounds fine.
You could also say "might"or "may" or "could" for that specific situation.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.