SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f0c6246a6fd9b0a46d8707a32ef9fbfbe06c92f6d1d769c98ecf5d6640a9568' 
  AND token = 'kF/FLoE3bLa6uVSj56QQkAFAgxEoxUgOA7w6OfFE61U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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