I have seent his error, which has prevented cron runs for over a month.

You'd have to resolve the underlying error by running the cron from drush and fixing whatever problem it reports:

./vendor/bin/drush core:cron

Note that not have the base_url set is NOT a problem, you don't need to set it in Drupal 8 9 or 10, and you can run it via drush like so:

 ./vendor/bin/drush core:cron  --uri=https://wasya.co

Now then, the trick that took me a while to figure out. There is no key_value responsible for the lock. Instead, you have to clear the table called semaphore:

select * from semaphore;
delete * from semaphore where 1=1;

This worked for me, and future cron runs were successful. Hopefully this helps you, if you've run into this problem!

.^.