SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '73af398634dbf345c3d9f850951b5dac1e098dab71a4cc366148ab6a56169bcc' 
  AND token = 'V/n/0K3kDF0ZWgUn4L94prw3E+mRhWyZcP57rj0fyc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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