Mysql consumes High CPU&RAM even after reboot

My VPS on DO (1 shared CPU & 1 GB RAM) sometimes got high CPU & RAM, and sometimes I stopped MySQL services then restart then it becomes normally, but sometimes this way did not work

Today, I tried stop first then restarted both MySQL & httpd services but it did not work, then I tried reboot but it still did not work too.

After reboot a few minutes, I used top command to see the stats below, can anyone help me?

phpMyAdmin alerts #1040 - Too many connections and declined connection.

Here’s my.cnf

# custom
bind-address = 127.0.0.1

skip-name-resolve
skip-external-locking

key_buffer_size = 6M
max_allowed_packet = 4M
table_open_cache = 48
sort_buffer_size = 384K
read_buffer_size = 1536K
key_buffer_size = 32M
read_rnd_buffer_size = 1536K
net_buffer_length = 4K
thread_stack = 480K
thread_cache_size = 8

innodb_file_per_table=1
max_connections = 100
max_user_connections=50
wait_timeout=50
interactive_timeout=50
long_query_time=5

query_cache_type = 0
query_cache_size = 10M
query_cache_limit=1M
#query_cache_min_res_unit = 2k
#query_cache_size=32M ## 32MB for every 1GB of RAM

tmp_table_size= 64M
max_heap_table_size= 64M

log_error = /var/log/mariadb/error.log
expire_logs_days    = 5
max_binlog_size   = 10M
innodb_buffer_pool_size=64M
innodb_buffer_pool_instances = 1
innodb_log_file_size = 48M

#innodb_force_recovery = 1

performance_schema = 0

[mysqld_safe]
log-error=/var/log/mariadb/mariadb.log
pid-file=/var/run/mariadb/mariadb.pid

#
# include all files from the config directory
#
!includedir /etc/my.cnf.d

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