SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc3276b6ec01c7963e2801a171edfba935d4bf5fb8c56fe95508676f41128218' 
  AND token = 'lIxLiRYMahmQueYz8VKqPwAptxDA+Uem9v+IJq7QJFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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