what is the syntax of an input key in a payload
I m trying to create a payload with keyboard shortcuts. in the wiki their syntax is only available for action menu.
for example should put control + 1 in the payload and {{1}} in action menu OR  {control}({1}) in the payload and {1} in action menu

The second part in your example is the right format.

Put {control}({1}) as value in the payload and {1} in the action.