from itertools import product
from numpy.random import rand
df = pd.DataFrame([[i,j,k,rand()] for i,j,k,m in product(range(2), repeat=3)],
                    columns=['par1','par2','par3','val'])

par1  par2  par3       val
0     0     0     0  0.464625
1     0     0     1  0.481147
2     0     1     0  0.817992
3     0     1     1  0.639930
4     1     0     0  0.035160
5     1     0     1  0.549517
6     1     1     0  0.172746
7     1     1     1  0.855064

conditions = {'par1':1, 'par3':0}

df.query(' & '.join(['({} == {})'.format(k,v)
                     for k,v in conditions.iteritems()]))

par1  par2  par3       val
4     1     0     0  0.035160
6     1     1     0  0.172746