SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6c2300862e6b45d402047dd96d3206d6d756ae7efbd790ac41b2d21838489207' 
  AND token = 'QvVlBbNSo44zVQzZq4f/LHouOlZTaS2xblFvYKp3pkc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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