SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5c3afefba8ae2e355c15ec1365777b79da125bc1abf66d5c92695bee02ce3565' 
  AND token = '2tJzjFa++OeRZiNpRDAguEHf+60eyhVGY/LwZSxuXz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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