SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b2d67ac35928932e95d545210f6efbfd2a9703d68b466d7e096ae814fe6fb2d2' 
  AND token = '2JwLajk+zRh94OHVUVA4tPDcEhtFgsAMkMnYLWILCYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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