I'm 72. Time did NOT pass quickly for me. I have never experienced the "where did the time go?" thought.
I think the reason is that my days did not blend together. I worked as an independent consultant for 35 years and did many different things for so many different companies in so many different places. As I was doing high level problem solving, I had many "first times".
People who do the same thing every day will have that blurring. People like me don't.