SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4da42baf43121d67644cee747921d1cb770644e963292c1ecbb2d08fdfdf2ccb' 
  AND token = 'dLIe9Eo4dTUbWRGOa83ZOakR/P+pPzozIPanrJ9Qt34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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