SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db08f56f7102dd7eeba949470e416f72604e51e6d9e249f45d189780eaf1b6e4' 
  AND token = '3jjpfxlL8nuuoWON0rPA3fgs+rZHuoA4mS9kzWjsul8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}