SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd23cb328a23c9b348de19b699504f83b753b368cc3879c75ea55906881b6c37c' 
  AND token = 'u7Lh3Uk+dsk6TMPntyQWjhhySyhBEj5sP2xf9temEfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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