SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96626c291a43931bed7fddd671fbbb00b4bdd697c67e0d5f65459308af3ab714' 
  AND token = '84vedfX9vXa0sIcyiRbbZWXqYFljTparehfbFpfU0Uw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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