SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bcdf51346b0cc52eae3e82637ded79a6ff63b424a4761d9718efc024d2b5518f' 
  AND token = '6fVmDDcLNUD4a8m5sTkAZyrUqr5iqxGmzrveNbOeaZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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