SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a148fd1d64fcb28efe430e1ac81a4b7080f2650a43b1a435770569c84f967c7' 
  AND token = 'AVBF2BfkxUxlYduYFqeNeIgm3wzXKCbEdLQTnMAMoRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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