SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9128e991944865aa2ec956635c44f268932f4d036b51269110eed5754bbba4ec' 
  AND token = '5Xrx3RxYIJqj5N3cdZkUWIUz/XfyhjDtLgoCR6J+Ks0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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