SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bfc3795967e385a3a21870ccc2d9fd37ac783ac1164c6b787dedf269116a7432' 
  AND token = 'bRmPpql1b/7rMEEGHf7HRxTnPLesFlUXTPLYo7lYTH4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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