Indexes increase data access performance. I tried creating indexes but there was no difference in the time cosumption. Am i missing something here?

My schema looks like this. (49 Columns). Id - PrimaryKey (Clustered Index) 

```
Id | Name | Age | CountryId | CourseId | ....... | EnrolledOn

```

There are around 425,000 records in the table. Considering country and course are the columns used to filter the records, I created a composite index comprising these two columns (These two columns are foreign keys).

I tried the following query.

```
Select * From Students Where CountryId = 1 And CourseId = 1

```

Without indexes and with indexes the query took 11 seconds. 

> 
> Note : Around 415,000 records match the above condition. Will this be a reason for no difference in the time consumed.
> 
> 
> 

Can anyone help me on this.

```
CREATE NONCLUSTERED INDEX IX_Country_Course ON Students(CountryId,CourseId)

```