SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e1e51382eab34b968b0a7878d1adbf7339162bedce18dbc3caba9da4beb6519d' 
  AND token = 'OcQ/5U6xv29EhXLjr91BIcc2Axu8d5comiXr+tU6ixA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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