Problem:

Column A contains date and time values.
We want to count the number of entries with matching date criteria (cell B2) and a time value greater than the one specified in cell C2.

Solution:

Use the SUMPRODUCT, INT, and MOD functions as shown in the following formula:
=SUMPRODUCT((INT(A2:A6)=B2)*(MOD(A2:A6,1)>C2))