SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d9ed1896c4549cb3648dd7171e60e544e2d177ca80856aa17fda895eaed20c7' 
  AND token = 'gx1gwJNLhbRhXcjVoHMyPfIK0r0ZTFtHfMJZnzjKq/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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