Speeding up a MySQL query

Question

I have this query:

SELECT
    FIELD1, FIELD2, FIELD3, FIELD4, FIELD5
FROM
    MYTABLE
WHERE
    FIELD1 = .... AND
    FIELD2 = .... AND
    FIELD3 = ....
GROUP BY
    FIELD4
;

Note that the only thing I changed are the names of the fields and the table. My query does have 5 fields in the SELECT statement and 1 table in the FROM section. The WHERE and the GROUP BY sections also looks exactly like that: 3 fields with equals condition.

The fields FIELD1, FIELD2 and FIELD3 are both PKs and indexes.

The problem: The query takes almost 8 seconds to finish (and it returns around 30 rows).

The question: Is there any way I can speed up the query, that isn't server related (increasing cache, running the database in a more powerful server, etc...)?

EDIT:

Fields declaration:

FIELD1: VARCHAR(2)
FIELD2: VARCHAR(3)
FIELD3: VARCHAR(7)
FIELD4: VARCHAR(4)
FIELD5: VARCHAR(5)

EDIT 2:

Output of SHOW INDEX: http://ibin.co/1LSSwvr0CVpX

EDIT 3:

Output of EXPLAIN:

select_type: SIMPLE
table: MYTABLE
type: ALL
possible_keys:
key:
key_len:
ref:
rows: 2081601
Extra: Using where; Using temporary; Using filesort

EDIT 4:

Example data:

Chicago = 1 (neighborhoods 001, 002, 003) (neighborhood zone 1, 2, 3) (postal code 10, 20, 30)
NY = 2 (neighborhoods 001, 002, 003) (neighborhood zone 1, 2, 3)(postal code 10, 20, 30)
Los Angeles = 3 (neighborhoods 001, 002, 003) (neighborhood zone 1, 2, 3)(postal code 10, 20, 30)

Data

1    001    1    10
1    002    1    10
1    002    1    20
1    002    2    20
1    003    1    30
2    001    1    10
2    002    1    20
3    001    1    10
3    002    1    10
3    002    2    20

What I do:

Search all postal codes that match TOWN == 1 (Chicago) AND Neighborhood == 001 AND ZONE == 1 and then GROUP BY the postal code. I hope this makes it clear.

Answer 1

problem seems with your searching method just inclosed your values like field1='value' as these are varchar and you are using with out quotes. By this your query will use index and you get performance.

Note: There is no need to use index as mysql do it its own.