Optimizing MariaDB for wordpress

[admin]

I have a server with 2 CPU cores and 1GB of RAM.The server only run one wordpress site.My Server Stack is LEMP.I ran mysql tuner two weeks after setting up the wordpress site.
Here are the results

[!!] Maximum reached memory usage: 884.8M (89.15% of installed RAM)
[!!] Maximum possible memory usage: 1.4G (139.86% of installed RAM)
[!!] Overall possible memory usage with other process exceeded memory
[!!] Slow queries: 15% (629K/4M)
[OK] Highest usage of available connections: 9% (19/200)
[OK] Aborted connections: 0.75%  (4103/548857)
[!!] name resolution is active : a reverse name resolution is made for each new connection and can reduce performance

Here is my

my.cnf

configuration

 [mysql]

# CLIENT #
port                           = 3306
socket                         = /var/lib/mysql/mysql.sock

[mysqld]

# GENERAL #
user                           = mysql
default-storage-engine         = InnoDB
socket                         = /var/lib/mysql/mysql.sock
pid-file                       = /var/lib/mysql/mysql.pid

# MyISAM #
key-buffer-size                = 32M
myisam-recover                 = FORCE,BACKUP

# SAFETY #
max-allowed-packet             = 16M
max-connect-errors             = 1000000

# DATA STORAGE #
datadir                        = /var/lib/mysql/

# BINARY LOGGING #
log-bin                        = /var/lib/mysql/mysql-bin
expire-logs-days               = 14
sync-binlog                    = 1

# CACHES AND LIMITS #
tmp-table-size                 = 32M
max-heap-table-size            = 32M
query-cache-type               = 0
query-cache-size               = 0
max-connections                = 200
thread-cache-size              = 20
open-files-limit               = 65535
table-definition-cache         = 1024
table-open-cache               = 2048

# INNODB #
innodb-flush-method            = O_DIRECT
innodb-log-files-in-group      = 2
innodb-log-file-size           = 64M
innodb-flush-log-at-trx-commit = 1
innodb-file-per-table          = 1
innodb-buffer-pool-size        = 624M

# LOGGING #
log-error                      = /var/lib/mysql/mysql-error.log
log-queries-not-using-indexes  = 1
slow-query-log                 = 1
slow-query-log-file            = /var/lib/mysql/mysql-slow.log

How can i optimize the configuation to fix those issues