This is the preferences you should see. The menu set to Miscellaneous so Set Fill to Black and White appears.
I set my shortcut to Ctrl + Shift + X
Note though that there is an alternative (and IMHO better) way of quickly choosing black or white. Use the Swatches panel, rather than the Colour panel.
The advantage is, unlike setting the Colour panel to black and white, any colours you have picked or set in the colour wells, remain there. So four colours (or rather, two colours plus permanent black and white plus transparent) are instantly available to you. Plus of course, you can set your own swatches.
It is possible to set a keyboard shortcut for the Swatches panel, so it instantly appears.
That is also in Miscellaneous but you have to scroll down to find it. It's called "Swatches Page" for some reason.
That instantly brings the Swatches "page" to the front for quick selection of all your colours.
Swatches is actually a much faster way of working because unlike using the Colour panel, where you have to click on the colour panel, then use a shortcut to set the colour wells to black and white, when you click on Swatches (or use a shortcut) black and white is already there, permanently.
