SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a850bb93d067fbc859922b9755764a23fc61320cfbd63f4c9f6e744d2e5f7d05' 
  AND token = 'jITcBJ/XZnWFrftNS9AxgaDQ/8bh3ruDzce0YOTOUmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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