now after saving this file you need to run below command :
php bin/magento setup:upgrade
php bin/magento setup:di:compile
php bin/magento cache:clean
php bin/magento cache:flush
Then logged in to your backend admin panel - and check now configuration are unlocked and able to editable.
you don't required to do import for the same , if you just wanted to unlocked this settings.
One more step will be required in some situations I have run across: flushing the opcache on the server. This can usually be accomplished by restarting the web server process (Apache, nginx, or whatever).