One simple way of creating fetch fast is to use advanced find and render that fetch in javascript.
Open advanced find and reopen window by pressing CTRL-N
Create your query...dont forget to build your query in full-window not framed as in screen shoot
Replace your URL with one of below javascript calls
javascript:alert(resultRender.FetchXml.value);
javascript:document.writeln(resultRender.FetchXml.value);
Now view source for fetch command
Copy and past and insert in your callouts or what ever your building
The result when prompting (alert) advanced find query