1. Why do you need RewriteCond here that does absolutely nothing?
2. Target URL should be just normal link -- no need to escape all non-alphabet characters like you do \:\/\/.
3. That directive requires mod_rewrite module to be enabled on your server.
That's how your rule should look like:
RewriteEngine On
RewriteRule ^domian_registration\.html$ http://mysite.com/domain_registration.html [R=301,L]
OR as simple as (although including full domain name in URL is recommended):
RewriteEngine On
RewriteRule ^domian_registration\.html$ domain_registration.html [R=301,L]
If you do not have mod_rewrite enabled on your site, you can use this directive instead:
RedirectMatch 301 ^/domian_registration\.html$ http://mysite.com/domain_registration.html