SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fdbe0a80dcc535bbe2c7511b3df16e7488518d9d63443794ae64a5b840555b37' 
  AND token = 'IrozeXop0w426/EdRuY04m2/Up2KFRCwl7VpcjsHh28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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