SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '723d2c6bf760a4a1edea85e7cc50bdc6bdbad97c7930580701f901c16e89a5ca' 
  AND token = 'MCp2D34oWPCAYVODD+nh0lSUcg7Jk/YDpTrmJc/cLrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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