https://github.com/mleku/x-realy/releases/tag/vainstr-v1.0.0

if you are running any recent linux this binary should be the ticket. you can see here an example of it generating a key:

?jwt=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJnaXRodWIuY29tIiwiYXVkIjoicmF3LmdpdGh1YnVzZXJjb250ZW50LmNvbSIsImtleSI6ImtleTUiLCJleHAiOjE3NDg2Mjg0MDcsIm5iZiI6MTc0ODYyODEwNywicGF0aCI6Ii8xNDY3NTU2MzQvNDQ5MzQxMzQwLTc4MTgyZDBjLTM0NTYtNDM5NC1hMzg4LWJkMTE0YTk2MzhhNy5wbmc_WC1BbXotQWxnb3JpdGhtPUFXUzQtSE1BQy1TSEEyNTYmWC1BbXotQ3JlZGVudGlhbD1BS0lBVkNPRFlMU0E1M1BRSzRaQSUyRjIwMjUwNTMwJTJGdXMtZWFzdC0xJTJGczMlMkZhd3M0X3JlcXVlc3QmWC1BbXotRGF0ZT0yMDI1MDUzMFQxODAxNDdaJlgtQW16LUV4cGlyZXM9MzAwJlgtQW16LVNpZ25hdHVyZT03MTQ5YjAwNzlhMDRmYTE2YzIyMDUwNTA5ZjI5YTcxYTZiMjg1ODNiZGQ0ZTU0MzZhZGY1MWZmNTJmYzQzNDRlJlgtQW16LVNpZ25lZEhlYWRlcnM9aG9zdCJ9.uu7IjisMQIFod8QNe9781sTxGxLHpzAj5j3Turfnnco

i used the btcd btcec secp256k1 library before, and it took like 3 days... now as you can see, a key with merely 5 letters potentially not even a minute on hardware like mine (which you can see in the image also what it is)