From: http://www.bbc.co.uk/worldservice/learningenglish/language/2014/02/140225_todays_phrase_keyed_up.shtml

Keyed up

A bunch of keys
What is the key to success when learning English?

Today's Phrase

If you are keyed up, it means you are excited or anxious. It is often used with 'about' - to be keyed up about something.
Examples:
I'm really keyed up about the show tonight.

You've been keyed up all morning, Clive. You should take some time to relax before your exam.

Take note

What is the key to success? Do you know the key to happiness? What about the key to wealth?The key to something is the way to achieve it.
Example:
The key to happiness is accepting that you can't change everything.

Interesting fact

In English we talk about a 'bunch of keys', meaning a group of keys which are attached together. The group noun 'bunch' is also used for things like bananas and flowers when they are fastened together in a tight group.