Does Indexing makes Slice of pandas dataframe faster?

I have a pandas dataframe holding more than million records. One of its columns is datetime. The sample of my data is like the following:

time,x,y,z2015-05-01 10:00:00,111,222,3332015-05-01 10:00:03,112,223,334...

I need to effectively get the record during the specific period. The following naive way is very time consuming.

new_df = df[(df["time"] > start_time) & (df["time"] < end_time)]

I know that on DBMS like MySQL the indexing by the time field is effective for getting records by specifying the time period.

My question is

1. Does the indexing of pandas such as df.index = df.time makes the slicing process faster?
2. If the answer of Q1 is 'No', what is the common effective way to get a record during the specific time period in pandas?