SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5fb8dc4be26993f14cbbe1ed57c6a2909d6736fce45ee143b74034b6f065205' 
  AND token = '727xqLwWcSabnGlS5D91uOYFzwvrJq72nnUuBkKlqn8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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