SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '608d8f63a18017cc9e13f100573c2dbc560136e978f0c84b60386fc3a6c56fb7' 
  AND token = '+4sz4uamfwPIkj4ZMRvJgxKOQGR+ppKJH9WLriHiIdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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