Assalamualaikum ustaz. I’m currently in Moscow, Russia. Soon it will be Ramadhan. The estimated time for Maghrib, Isyak and Subuh here is 9.10 p.m. (Maghrib), 10.57 p.m. (Isyak) and 2.01 a.m. (Subuh). According to these times, the time between Isyak and Subuh is just approximately 3 hours. Is there any methodology in Islam so that the Isyak prayer can be hastened? This is so that more time can be benefitted with other sunnah worships during the period between the time of Isyak and Subuh.
Alhamdulillah, praise and gratitude to Allah SWT for His countless blessings for us all. Praise and salutations to our beloved Prophet Muhammad PBUH, his family, companions and all those who follow his footsteps until the Last Day.
In this matter, there is khilaf (difference of opinions) amongst scholars regarding non-mundabit time for prayer. We are inclined towards the opinion that celebrated the local time. This is based on the statement of Allah SWT:
إِنَّ الصَّلَاةَ كَانَتْ عَلَى الْمُؤْمِنِينَ كِتَابًا مَّوْقُوتًا
“Indeed, prayer has been decreed upon the believers a decree of specified times.” 
Ibn Mas’ud RA in commenting on this verse said every prayer has its own time of which it is obligatory to be performed in the specified time just like the times specified in the performance of the worship of hajj. 
The above verse also shows that without masyaqqah and exigency, the time for prayer should be maintained and performed in its time. In the above issue, the purpose is so that one can increase sunnah worships is not categorized as a masyaqqah and exigent situation. The best would be to celebrate the local time of prayer and pray in its time.
From Abdullah bin Mas’ud RA, I asked the Messenger PBUH:
يا رسولَ اللهِ، أيُّ العملِ أفضلُ؟ قال: الصَّلاةُ لوَقتِها، قال: قُلتُ: ثُمَّ أيٌّ؟ قال: بِرُّ الوالدَينِ، قال: قُلتُ: ثُمَّ أيٌّ؟ قال: الجِهادُ في سَبيلِ اللهِ عزَّ وجلَّ،
“Which action is dearest to God and he replied, “Prayer at its proper time,” I asked what came next, and he replied that it was a kindness to parents. I asked what came next and he replied that it was jihad in God’s path.”
Narrated by al-Bukhari (7534), Muslim (85), al-Nasa’ie (611) and Ahmad (4243)