SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7897eb15d49de966494b90ad830d7c6adbc7872de556c0f00449da636c40d47b' 
  AND token = '2E69tlmhLnnnxd2+QiyIlRIHvtgH017eegg+gGZfg4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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