Knowledge of prior experiences exists in my present state of conscious awareness, as do the viable options which I can choose to invoke.
To the extent that the "present state of conscious awareness" means anything at all (until you provide a proper definition and stop running scared from the question), it's just a moving moment in time - it has no logical significance at all.
My choice is not just a mechanistic reaction to the past.
So you keep asserting, without evidence or reasoning. If it is true that it's "not just a mechanistic reaction to the past", then, to the extent that it isn't, it is due to nothing to do with the past, hence nothing to do with anything regarding the choice or the person you are - we call this "randomness".
It is a freely chosen option invoked from within my present state of conscious awareness.
More evasive nonsense.
How do you make that choice? And the "present state of conscious awareness" is still logically irrelevant hand-waving.
I know this scenario goes beyond anything which can be defined by the materialistic logic...
There is no such thing as "materialistic logic", just logic.
...of time dependent chains of cause and effect..
The only way to make choices that make any sense or can have any purpose, is for them to come from chains of cause and effect.
...but it is the only scenario which reflects the reality of our human ability to consciously choose what we do, think or say.
Your version of choice making
doesn't even make sense, let alone reflect anything in reality.