SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'eb730646ea8111bdc6409f263f6431497bc507bbc1b34d05e071819e233783dc' 
  AND token = 'oNQIKOaL31iEZqzhI7nOBRiWmdpLZg10uZX7iHzkKZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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