SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28d6b852694b4f388f160cbc10a36d05c7c7d6baaeed8d44e2675b962515d2fa' 
  AND token = 'zIlgjSiR/0MI7PmidyRg+Ht9KUW49db2etk/YVvUbhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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