SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5951b7ceb184c1da704de143abe434e63cb03c45f7aed69d9e69e5daf9fa3cb' 
  AND token = 'RiTLKODvGn/mWcnDlHJSv4Pqtn5CQ5QYOzh1sBjdDE8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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