SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a121cf56d858ae601df126b2c731305bd4c29c0d62093179a4b2ecceeded6849' 
  AND token = 'FDbL08sUawZ0aE2+XRdtZrqIzgspQMFICleeB+Ia4ng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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