SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87b659cdc9419e21090f03df4fddcc1f1fd0e086c8cb7f97918a5a13b8731078' 
  AND token = 'QjhBG+jxG3thQPsHq7e25qfifk/8TNz7I8AceCCtbyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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