SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '966b2e140f7819aa19109b05757b4d67e842308bfbaa46f02be51a8055c30171' 
  AND token = 'fcNPyUQraOys1R0BI97CKleMFRJ+J++NsXjElm1jWs0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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