var1='C:/my/store/path'

myimage_1010_im.png
myimage_1010_im1.png
myimage_1010_im3.png
myimage_1020_im.png
myimage_1020_im1.png

var1='C:/my/store/path/myimage_1010_im.png'

import os
cwd = os.getcwd()
my_file='1010'
path = os.path.join(cwd, my_file)

import glob

var1='C:/my/store/path/*'

paths = glob.glob(var1)

my_file='1010'
selected_path = filter(lambda x: my_file in x, paths)