SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd1547eaaee697b49c3ca4855468f115b351bdab2664d8dba5f31299c683c7b7a' 
  AND token = 'PXPeRdbWxY0yzRPYsuzOvZ2X9FCCdWRUldfnbItw55Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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