something like:

json
/* in keybindings.json. 
* Use `Preference: Open Keyboard Shortcuts (JSON)` to open.
*/ 
[
  ...
  {
    "key": "{desired keybinding}",
    "command": "dendron.lookupNote",
    "args": {
      "noteType": "scratch"
    }
  },
  ...
]

here are the relevant docs for reference: