SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29306263d6df553007ff8ba267df1a101583d075fc9b14ad238eafd6cda4148a' 
  AND token = 'cBs2lN97knQlzVpE8AInQYdjxTl8738e8t+uZ5VTfFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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