There are a couple of ways you can do this. This is how I'd do it in Electrum:

1) Replace by fee - In electrum there's the ability to go to "If fee is too low" or "Always" from Fee preferences in Tools. This would've then let you select 'Replacable' to allowed you to later on replace the fee of your existing transaction. Could you check if Mycelium allows this feature? I'm not sure since I haven't used that wallet. I believe I was able to do this in electrum by right clicking on the unconfirmed transaction -> selecting increase fee --> then setting a higher fee or using electrum's dynamic fee that was already set.

2) This is possible now if you're receiving the funds - Child-pays-for-parent  - In the 'History' section right click on the transaction that is unconfirmed and then selected Child pays for parent -> increase the fee this time to a suitable fee (calculate it from here: https://bitcoinfees.earn.com/) -> Sign and broadcast the transaction.

3) By using a transaction accelerator like confirmtx, viabtc's tx accelerator or antpools tx accelerator. I've accelerated your transaction on confirmtx and antpool's accelerator. It might get confirmed in upcoming blocks when they include your tx in their block that is mined. If you can't wait for this option to have your tx confirmed, follow option 2 if you're receiving the funds.

Edit: Updated post after confirmation.