SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e873bee261ca7955d01b2b9d5dfc69e3e81b5ec8c432601475b9c1c5cfb10366' 
  AND token = 'da2iDusA4dgsWxNsetY22S56lVUYuFbsEdSxbTbf7Tk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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