SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bbc4f1588f354c73aa96d3074e562be41072353278eb17a58b65000131f3fe6' 
  AND token = 'DUFyJBUTwvPaMtZYJjZr++/4aUvpIoYc50/QD5YMlwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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