Follow these steps to add a keyboard shortcut to the in5 export within your copy of InDesign.
- Edit > Keyboard Shortcuts
- From the Product Area menu, choose Scripts
- Find Export HTML5 with in5...(or Easy Export Wizard) from the list, and select it
- Click on the New Shortcut field and type the keyboard shortcut that you wish to use
- Click Assign to apply, and OK to close the dialog
The steps are also shown in details in the video below.