SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1912e24f5e6e64d7c65643841cf767891e95f698942b2bc7a00faaa3ffc64868' 
  AND token = 'zOJ9AljmkVcYgOfSzElL7sXqIGwJk/95bYqDkisSa70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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