If you get a rapid decompression (used to be referred to as explosive but that term obviously can cause confusion) at altitude there's a figure known as Time of Useful Consciousness (TUC) hat comes into play...
That's the interval between the decompression and the time you become unable to think/act in a useful manner if you don't get onto supplementary oxygen.
At high level (airliner cruising levels) that can be a large handful of seconds, at lower altitudes it can be a miinute plus...at the level the recent Ryanair event happened many people might have barely been effected, especially if they stayed seated and weren't doing anything mentally or physically challenging.
skybrary.aero/articles/time-useful-consciousness