Every Air Fryer is slightly different however going on the premise that heat rises, if your air fryer opens by sliding a basket out from the side or front, then there should be no reason why you can’t open the basket for short periods of time. If your air fryer opens from the top by lifting a lid off then it’s probably not recommended due to all the heat escaping.  In these types of air fryers though, there’s probably a see through lid.  In short, if you have a Philips Air Fryer, then yes, it’s perfectly safe to open the basket for checking or shaking the basket, any other air fryer should be okay as long as it slides open from the side or front.  If in doubt though, consult your manufacturers user manual.