SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90a726a8cb94f42e47c8ac7f467aac68b45bd5d912f927009703f0e694198c3c' 
  AND token = 'nHab+59t9oIgOubAbuqocD9hbJKwLZYqtgk1pErgZlo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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