to get a better understand of how transactions make it to a block please read the following series of FAQs starting with this one and all that follow till the end.
I hope it will help understand the topic better.
first of all please consult the multi-index table documentation:
in your question you say you want to query the table without using the primary key and later you say you want to query it based on asset_id; but it seems asset_id is your primary key. I assume this is a typo and ...