SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7626cab21475a0a18fc33edf6039c3ff6c544f634015cdc1a6337ac5b236d7de' 
  AND token = 'MpVCufCZ7jWhfdm66R4Esk7QRN+5c5gUE+CG78688PE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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