SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82db5cdb8bbb96271ea276c615cc80feaf43f584e88cb1a5778408cd78c3c0e2' 
  AND token = 'GUaubKArfi+dTcBKZIBSbUxsSomfOQ+Z3mWqrIoxdMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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