SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '617b32707fb3de5177e13efcd1fb97450a1eef987ad20340269462638fe5cfb7' 
  AND token = 'rJ9xnWmJWRLzuXepNkUIn4F8VXbFMMp2TKT4/2jhq1g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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