Like many other applications, App Store has keyboard shortcuts associated with it for alternative navigation.
Command+Q – Quit App Store application
Command+H – Hide App Store window
Command+W – Close App Store window
Command+M – Place App Store window in Dock
Option+Command+H – Hide all other applications
Command+[ – Go to previous page
Command+] – Go to next page
Command+R – Refresh page
Command+F – Search
Edit shortcuts:
Command+A – Select all
Command+Z – Undo previous typing change
Command+X – Cut selected item(s)
Command+C – Copy selected item(s)
Command+V – Paste selected item(s)
Command+Shift+Z – Redo last undo procedure
Option+Command+T – Input special characters