My first answer would be that it’s not the time it took to commit a crime that warrants its degree of punishment. Rather, it is the severity of the crime that bears on its consequences. For example, a murderer could commit a homicide in less than five seconds. Yet we would agree that this murderer should get a heavier & more sever sentence that someone who has taken three years to extort money from a company.
However, it is who this sin is directed at that really matters here. Sin is always directed at & against God (Psalm 51:4) and since God is an eternal & infinite being (Psalm 90:2) the punishment warrants eternal consequences. Because God is righteous & holy he will not turn a blind eye to sin nor will he tolerate it. The Bible even tells us that God’s anger burns against the wicked and disobedient (Isaiah 5:25, Hosea 8:5, Zechariah 10:3).
So, it isn’t the temporal nature of sin that ultimately matters in determining consequences. Rather it is who this sin is directed at that determines the punishment – and since God is an eternal sin requires eternal punishment.