SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b8d8e4092188fab209d4871712edc191dc634720a3cc3f66144c50fd3208155' 
  AND token = 'y1obZEBl8OVjrCwzPYqmZces4z1GrzDV9yFtmuUsUJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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