SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4935f385b789f7a59caf3be3dffd26f0a951a7f2353fedaef9eaeea5c544e306' 
  AND token = '5ezC4yqTQYPnl4+rlFM0nxSMB7KgTXF/u7PRsI3lfl4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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