SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c9d3fd576dbc78bfbe684f1f238405d8b8e385efdae49d7473465b0389e22dbb' 
  AND token = 'BC0HQ+IUNqFXn4cuc840/5av/eEpZSqevtlumSTwjws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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