Question

is it possible an object with a constant acceleration but with zero velocity

Answer 1

An object having constant acceleration must have velocity as acceleration = velocity / time or acceleration is proportional to velocity.

But, when the acceleration of a body is zero, it has a constant velocity.

Answer 2

constant acceleration means velocity is constantly changing,
your object may have zero velocity,but just for an instant
[like a ball thrown into the air,at the highest position,its velocity is zero,but it can't stop forever there]

Answer 3

so, the answer is no.