SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81b5e09adcd0cc8b67305636a7383e08ea708a74c9e8f30de54a77673f683b43' 
  AND token = 'JNQy6BdiIHHMXm2aX5U7sf0xZxm5lDQEKCZ631zBZBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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