SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd54fa297bf77cee6153f638c535910167b8de710661f6c74745d7fde39ead122' 
  AND token = 'Ps11zFZn6wm8j3mKtnnHFrtiOMR4saZGfYB0KWSJyV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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