I haven't yet found one that I can. I've asked several people who claim that there is no problem, how do I get into UEFI setup, to turn it off (or add my own keys)? The thing is, while Microsoft turned around and added a requirement to be able to turn UEFI off (originally, they weren't going to), they also made a requirement that to boot faster, it was not allowed to let people press a key to enter setup.
Hold the key down before powering on (and keep it held for a second or two after). On a Toshiba the key is F2, and it will definitely get you into the setup. On other brands you could try ESC, Del, F1, F2, F4, F10 or F12. Microsoft seems to think that you can access your BIOS settings with a keystroke. Have a look at their instructions on how to Disable Secure Boot:
Open the PC BIOS menu. You can often access this menu by pressing a key during the boot-up sequence, such as F1, F2, F12, or Esc.
Or, from Windows, hold the Shift key while selecting Restart. Go to Troubleshoot > Advanced Options: UEFI Firmware Settings.
Also, if Windows fails to boot 3 times in a row it will enter the boot menu, from which you can access the BIOS. Try booting, then turning it off three times. I had to do that once when I had a hardware fault once.
And no, the signed Microsoft Linux that some distros use for setup is not a valid option either.
Or you could use a distro with a Microsoft signature. Good suggestion. Oh, except for some reason you don't want to run Linux.