Where is the admin path located in database?

I don't think Magento 2 admin path is stored in the database.

You can find the randomly generated path in the app/etc/env.php file, e.g.:

'backend' => 
array (
  'frontName' => 'admin_1ai8c5',
)

Also an easy way to retrieve the admin path is by using the following Magento 2 CLI:

php bin/magento info:adminuri