Locked myself out

Beside this great plugin I use a plogin that leads me to a custom login site. The problem now is, that this seems to leed me to the under construction site. The result is, that I can’t login anymore.

The only possibility I see is, to set under construction off in the database and the question is, where can I find this flag?

Thanks.

https://wordpress.org/plugins/underconstruction/