I just tried printing the key on paper. I scanned the paper with my
Fujitsu scansnap at max resolution. Then converted the resulting PDF to
a jpg with ImageMagick. Then OCR'd it with tesseract. No joy. OCR is
just not good enough.
OCR success depends a lot on the font used to print the text being recognized. Have you tried different fonts, in particular OCR fonts? There are some free to download at
https://www.wfonts.com/search?kwd=ocr (and probably elsewhere), might be worthwhile to print the key using one of those and seeing if recognition improves.
If you place an image in Google Drive, and open in Google Docs, it does a very good job with most fonts. Obviously you'll have a lot more luck if you encode in Base32 and use OCR-A. (or Base64 w/ OCR-A Extended).