SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1df305bfdb3648965cd45f8f135dc550f190270066295387756f27577cbc670d' 
  AND token = 'Z6HkylQipEEcLCoRMaQEL9zMqsJoOlDmKMT4dH1RzPk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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