SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2d93af5481ea62f6596015dda106f97d34f95e3db81014f1b176d409ca4d241' 
  AND token = 'JhBtpy9QdPsV4WhOLaPGbJrrSTsK8aotg2QFCRA6S4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}