SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1845a056eb6b867dd30ffc57816e561bbbe8fc4da07cb024ae5ba9a3342bdb21' 
  AND token = 'syJqK1HFqZlz0QMMDUR3G8CjZ5Wv4thylJMfyAIzuFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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