SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9effce3d69f286bc833b131fafca989d7bffb7a0be8598e61c0c4fa88564fbc6' 
  AND token = 'xmKKmDMMMcmmMGZQ1E2W5GYaNhfrAIYyNGUtk9v1VAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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