How to rewrite location for nginx more "beautifully"?

Question

Nginx

Friends, hello. To access phpMyAdmin installed from the repository on CentOS 7, I have the following location in the nginx config:

location /pma/ {
  alias /usr/share/phpMyAdmin/;
  try_files $uri $uri/ =404;
  index index.php index.html index.htm;
  location ~ ^/pma/(.+\.php)$ {
    fastcgi_pass unix:/var/run/php-fpm/php-fpm.sock;
    fastcgi_index index.php;
    fastcgi_param SCRIPT_FILENAME $document_root$1;
    include fastcgi_params;
  }
}

Could you tell me how to rewrite it more accurately? In order, firstly, not to repeat in two places /pma/, and, secondly, so that nginx gives a 404 error to non-existent php files, and not No input file specified.
Thank you for your advice.