SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9bc157e80e279af61378c32ae7a7d6e0d714423857c3378604ec449547bee9f6' 
  AND token = 'VseHvxbCZY1y1YDlwewqaZcDttHB2gcyQM5hHPOIb3I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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