SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d5213f4a64684acca1ba502bf7562a6cdb576231e99ad30ef876f7a162d1eef' 
  AND token = 'JK6jIM+Ruw8Hj5/khtAwCAE9OPjVt3CxF9qVZ1NE8EQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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