The file is not going to be accessible over the Internet. There is nothing offering the file to remote people.
What can happen, though, is that someone can hack in and gain access to your computer, and from that level of access, gain access to any file on your computer.
The most important protection for this is to do exactly what you have done: encrypt and password protect the file.
As an additional measure, you could store the file on a removable drive and disconnect the drive when you do not need access to the file yourself. This is not as secure as it sounds because once you connect the drive, then anyone who has hacked into your computer could then also access the file. But it is an additional measure.