SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '80eca42f772e858e82210f5461fea72b6dff999de500b017d78cabf463c5e736' 
  AND token = 'OKyj37HVfvybrujTJbYFdbAZ9WsLoLOuBjWxBP+cWck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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