error 504 time-out while updating ip2nation data from wp-admin

I’ve installed Custom Content By Country plugin on a clean WP installation recently. Straight upon installation a notification popped out for ip2nation data to be installed for a proper plugin work, however once I’ve clicked on a button for ip2nation database to be installed (https://website.com/wp-admin/index.php?CBC_INSTALL_DB=install), webserver returned me 504 error.

I’m running wordpress on nginx + php7.0-fpm

nginx error log returns
==============================================
2017/08/30 08:41:25 [error] 31273#31273: *47 upstream timed out (110: Connection timed out) while reading response header from upstream, client: XX.XX.XX.XX, server: website.com, request: “POST /wp-admin/index.php?CBC_INSTALL_DB=install HTTP/2.0”, upstream: “fastcgi://unix:/var/run/php/php7.0-fpm.sock”, host: “website.com”, referrer: “https://website.com/wp-admin/plugins.php?plugin_status=all&paged=1&s”
====================================================
php-fpm error log returns
——————————————————
[30-Aug-2017 08:59:20] WARNING: [pool www] child 31703, script ‘/var/www/website.com/wp-admin/index.php’ (request: “POST /wp-admin/index.php?CBC_INSTALL_DB=install”) execution timed out (157.062445 sec), terminating
[30-Aug-2017 08:59:20] WARNING: [pool www] child 31703 exited on signal 15 (SIGTERM) after 160.007473 seconds from start
[30-Aug-2017 08:59:20] NOTICE: [pool www] child 31726 started
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in php.ini i have following:
========================
max_execution_time = 90
max_input_time = 90
======================
i’ve tried to increase both values for up to 5 mins, same result

in https://www.conf
request_terminate_timeout = 90

in vhost nginx config in location block for root directory I have:
fastcgi_buffers 8 128k;
fastcgi_buffer_size 256k;

Any idea what I might be missing here?
please note, there are several websites hosted on the server and none of them had problems with nginx-fpm timeouts till this moment.