Fixed condition to check expired token for exec auth

[ankitabhopatkar13]

Fixes #228

It also fixes the issue where if the token is valid it was regenerating every time.

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[ankitabhopatkar13]

Signed CLA

[ankitabhopatkar13]

/assign @brendanburns

[brendandburns]

/lgtm
/approve

Thanks for the PR

(we should really add a unit test for this)

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This pull-request has been approved by: ankitabhopatkar13, brendandburns

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