SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4a7ef58d8f1900ea9e1532f3191f1d5aa7b776181b7f7c7255b3549967b579a5' 
  AND token = 'luJgEY6Y53sqnP035cwchBDaceB1hj+dxq1PE4BFTXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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