The S3 presigned URL expires at the time the credentials used to create the URL expire, from the documentation:

If you created a presigned URL using a temporary credential, the URL expires when the credential expires. In general, a presigned URL expires when the credential you used to create it is revoked, deleted, or deactivated. This is true even if the URL was created with a later expiration time.

This is why you see the URL has expired before 48 hours. It is also only possible to create presigned URLs with expiration times greater than 36 hours by using IAM users with an access and secret key.