Once you have the extension installed, a small search bar will appear just above your emails. Using it is as easy as typing in whatever you want to search for.
With only the first few letters of the name of the email, for example, this extension can find exactly what you're looking for.
CloudMagic is a relatively interesting extension for any Gmail account. This is especially true if you have more than 100 emails, at which point it can become very difficult to find the one you need.