SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '85aee060f741f0bde2102bb3e4de5e461178092b42403e261f60ed8eb5a62e44' 
  AND token = 'S/v6jjILDft44e2iqWywZ9OE7WJSp5gnnNnJOhYiO+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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