SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '879fed41eb8e91cc41739940a3ba451aea1a36d1cb3f19ccc7509f026136530b' 
  AND token = '5NFINLdjf0fGgK5XtUviynhyCA6o3LRFDw8NjTT2+y4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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