SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'baf0cd8f104eca6bef9dfb299ceca3f7f7de200b490aab19899cffe14b90b1e9' 
  AND token = 'gN80phLyHuPZb6WvkvFhmOj178NL/TQZej0YsXbW5f8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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