SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd026438b6315467e1f47d6ff158b95a83a335f909d1d81637169e98ca7ac9002' 
  AND token = 'qRmTwCvRo4UV4/hy2VB/tEuBpU+auUHpy8PlV64juaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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