SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '2bc3b115d8f897250871055904893c2c45f1ebe18c6dc6db50a267509242dc58' 
  AND token = '+b4qwEMj0ItSHap2xbBBMDddkYF+txBF+HrgB2+zk3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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