SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '14a505dd4da85168cb9282cb51874971bd842ce02f9b870a50588c586d8271b8' 
  AND token = 'tSYZoKrQooM5UlcAxiwENxMIxnZ3OmV1hbGGZ9cyVRE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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