SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '917910d7f92f203651dbfebeee9f8c6202e8d3e3bf8d1437ae0160f24ba26966' 
  AND token = 'JIKp9IappeXSQFJKwH45ukeGam+L/8vnGVbnYyuueJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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