SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd35728f913a1d4e16407910c5ea34c4b05bbe97d242119fb87a4f01ab425faa2' 
  AND token = 'Mq7lvOi2KcvSX5kdgPhfHc6AJ0+B4IGhcZU+SpcB6DY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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