SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '280e343b8c807f28711ceb35b1c0af0951c7f84c9ef7e9c26f8e70f70b194498' 
  AND token = 'YMEhBLfmVkZHWRwCb4AsZDrrvRRXul9pQj9z0KHpYvs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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