SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c9f3054783ee0fc8de29b3b45698676502414dd80f259ef4257c78131e7f5542' 
  AND token = '892or8QzCNQvHykigkTJ7qYtFTB5e3/srIV+YVKn+pU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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