SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd21b6ea019be9ced62faeb806ae31081e112616facfb27e5709446f22ee384bb' 
  AND token = 'eWZHxUyERDoEOfbvC7Czac1tl0gNxMfUeeoZYccDPYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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