I think my access token for my scratch org expired. I'm using sfdx in visual studio code. What's the easiest way to get/fresh my access token?
The easiest way to refresh the access token is just to open the scratch org via Salesforce DX.
From the command palette, you can do
> SFDX: Open Default Org. Or, from the integrated terminal, do
-u my_scratch_alias to select a specific org.
Once you do so, any other functionality you might use that depends on getting an access token via SFDX should work again, provide the scratch org is not expired.