For finding features located within a specified distance, PostGIS is equipped with a specialized ST_DWithin function. It can be imagined as a combination of ST_Buffer and ST_Within, only it omits the buffer geometry construction step and is much faster.

The syntax is as follows:

ST_DWithin(tested_geometry,reference_geometry,distance) 

Let's look at an example - listing all villages located within 10 kilometers of Rybnik city:

 SELECT name,wkb_geometry FROM points WHERE place='village' AND ST_DWithin( 
    wkb_geometry, 
    (SELECT wkb_geometry FROM points WHERE name='Rybnik' AND place='city'), 
    10000 
)