RewriteEngine On

# prima forziamo .php
RewriteCond %{THE_REQUEST} \s/signup/inscripcion/index[\s?] [NC]
RewriteRule ^index$ /signup/inscripcion/index.php [R=301,L]

RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]