SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '08729b2bee00ba587820e28f9adf8ef57e55f60734f214f9ea1a702ebcae4d6f' 
  AND token = 'fLjqrMqtKvwVgsyM5Ao0mhXhzi1jRPcJtHrL84NlCRU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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