SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c5c0de62b5c5ff9d3c8c3657ebc100db49e0444d904c50b22bb56bb26a308850' 
  AND token = '21lu5pDr9yCps2rXwUGzejjUJCW7Ng++tWFNI+qJq1Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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