SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '766ddcac2cee60390e55df0e2293f5c28145f9aacbdd98c3b7b836c17338c362' 
  AND token = 'dTo+NwuLC+h1PjK5ug23zk8dbHtB8QmwYFHYZdzvYeU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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