Calculating DES key knowing message before and after encryption
A single p3.16xlarge EC2 instance is capable of evaluating $369\times10^9 \approx 2^{38}$ DES calls per second using hashcat. 

This puts the maximum time to recover a key at around $2^{56} / 369\times10^9 / 3600 \approx 54$ hours. This costs a little over $1300 at current pricings.