Ctrl+1 is the shortcut for a 100% zoom.
Go to View → Actual Size

If you want to input a custom zoom level after pressing a shortcut, you need to use a script.
var zoomLevel = prompt("Percentage:", "100");
if ( zoomLevel ) {
zoomLevel = zoomLevel / 100;
app.executeMenuCommand("fitin"); // Centers the artboard to the window
app.activeDocument.activeView.zoom = zoomLevel;
}

If you want to define a shortcut to launch this script, you need to use third-party apps to tell Illustrator to open the script file when a shortcut is pressed.
There are many ways to do it. In this answer, I list 3 different ones. A way to do it in windows is at the bottom of the answer.
There is also the Window > Navigator
but you can't set a shortcut to focus on that input.
Someone in that other question says Illustrator now (CC 2018) remembers it if you record an Action that opens a script, which would allow you to then set a shortcut for the action. This has been a problem in the past because AI would just drop out the script recording after a while. I guess on restart (maybe). I forgot.
I'll throw this in too, since I happened to make it. This code zooms all documents.
var aDoc = app.activeDocument;
var zoomLevel = prompt("Percentage:", "100");
if ( zoomLevel ) {
zoomLevel = zoomLevel / 100;
for ( var i = app.documents.length; i--; ) {
var activeDoc = app.documents[ i ];
// "fitin" = Fit artboard in window
// "fitall" = Fit all artboards in window
// "actualsize" = Actual size (100% Zoom)
app.executeMenuCommand("fitin");
activeDoc.activeView.zoom = zoomLevel;
}
app.activeDocument = aDoc;
}