Can you choose to cast a lower-level version of a cantrip?

As a 1st-level character, the Warlock cantrip eldritch blast can be used with the Twinned Spell Metamagic feature of the sorcerer.

However, when a character reaches 5th level, eldritch blast becomes a spell with two possible targets, and can no longer be twinned.

Can a 5th-level character cast the 1st-level version of a cantrip?