PostGIS Spatial Relationships query performance

I have a very large dataset contains over 700 million points and a polygon dataset as a buffer zone.

My task is to extract all points inside the buffer zone and create a new table.

Below is my code. I test it with a small point dataset and it works fine.

create table schema1.result asselect point.* fromschema1.site as point, schema2.buffer as polyWhere ST_Intersects(point.geo_loc,poly.wkb_geometry);

Unfortunately, the query lasted for 1 day and showed no signs to finish.

Is there any advice to optimise my code to speed up the query?

Update: The output of Explain

"Nested Loop (cost=0.41..17773703.88 rows=6789472 width=208)"

" -> Seq Scan on buffer poly (cost=0.00..18.50 rows=850 width=32)"

" -> Index Scan using idx_site on site point (cost=0.41..20902.23rows=799 width=208)"

" Index Cond: (geo_loc && poly.wkb_geometry)"

" Filter: st_intersects(geo_loc, poly.wkb_geometry)"

"JIT:"

" Functions: 6"

" Options: Inlining true, Optimization true, Expressions true,Deforming true"