SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c81449c974c12be09b5de4e179f028e606b32563136c8bb569d5d99339c514fc' 
  AND token = 'X6d19SZ8/SmoDrde6GXnGzjVadggLfvMLTBMNHlhqL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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