You currently have two options.
1. Wait for it to be mined or contact another miner for help.
2. Remove the transaction from your Electrum manually and try to send another transaction which spends that UXTO.
For 2, follow the steps here: https://bitcointalksearch.org/topic/m.17301306. Do it at your own peril, always make a backup.
You should update Electrum as version 2.5.4 is quite old and the newest version includes a lot of bug fixes and features that address fees a bit better. I definitely recommend you upgrade and ensure that Dynamic Fees are enabled for the best experience.