SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15271735ae74a72718d740f35a86e5dab71d1a41906ee619e2074066910c9130' 
  AND token = 'uBhWf9cKUvnT8SY/90lt60wf9zwiBa+oRzU+VgTkS14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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