Yes you can easily toast frozen Ezekiel bread without thawing the bread out first.
As you toast the Ezekiel bread in the toaster it will thaw out on it's own and toast.
But the frozen Ezekiel Bread will just take a bit longer to toast the bread but it will toast just fine and sometimes on some toasters there's a setting for toasting frozen bread.
So if your toaster has a setting for frozen bread you should turn on that setting before putting the frozen bread in it which will toast the frozen bread better.
Then you won't need to adjust the other settings.