SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '688613deb26ddeacd692adf6d90fe8115e2c5086d8bfa42ddb3d612b7791c7c9' 
  AND token = 'P2e4c6pwCte3V/oKEFUnc9qISFkiJq6V5N+Gdb3LxaM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE Impossible WHERE noticed after reading const tables