SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76d2b3c118f2956731a7c3aa62334164a23797f768eda05b1c2522273d555a19' 
  AND token = 'j7d+YgdPa6S+U/PLXgOQv+oPB/b3huK29DzP3UZZge0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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