As [mysql_real_escape_string()][1] was deprecated in PHP 5.5.0, and it was removed in PHP 7.0.0, you can try [esc_sql()][2] to work for later WP/PHP versions. 

Replace `mysql_real_escape_string()` with `esc_sql()` at line 111 & 118 in your `admin-interface.php` file.

Hope this should work well for you!
  [1]: http://php.net/manual/en/function.mysql-real-escape-string.php
  [2]: https://codex.wordpress.org/Function_Reference/esc_sql