SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '28d4e86d6fa8872044e4591fd17d66772ade015ba49981bbd3096031cc7c2b04' 
  AND token = 'MNoii2qfC8BiRATTydc/vVaI71Jmxd6r6hqWSIy3zpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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