Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_2 (fastest_lap VARCHAR, constructor VARCHAR, race VARCHAR)

### Question ###
What was the fastest lap time at the British Grand Prix with Mercedes as the constructor?

### Accurate SQL ###

SELECT fastest_lap FROM table_name_2 WHERE constructor = "mercedes" AND race = "british grand prix"