SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b3bf2a6b9a39e108ed63ad7a9df20930ee9f19ba0a1a183785678344fed8737c' 
  AND token = 'OjJP7Amrn0es0AjOFeM26STAmfPK6Vusv6emzce20kU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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