Strictly speaking, yes you CAN generate 5 second delay in interrupt. But you really, really should NOT do it.
And if you are going to do it anyway, it could not be easily done with delay(), as Arduino supports only one level of interrupts and delay depends on interrupts enabled. (which can also be cheated away, but it should not be).
The right thing is use interrupt for fast detection of key pressed and manage other parts in loop(), see https://www.arduino.cc/en/Tutorial/BlinkWithoutDelay how to wait in main, while doing other work.
Also using lcd and Serial inside interrupt can bring a lot of problems, especially if you are using it also in loop() (as the key can be pressed anytime and interrupt can well -interrupt- such commands in the loop and then make your output all wrong and possibly crash your program on the way too.)
Read http://gammon.com.au/interrupts if you want to know more about interrupts and why your idea is not the best possible way.
Question: Can I hit really hard my thumb with heavy hammer?
Answer: Yes, you can, but you really should not do it. There are much better ways for using thumbs and hammers.