SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd74de624b3262621c4aedef406ffedbf6867a7612b60ab754786e6419f8214c9' 
  AND token = 'BnMvcSendBr8/jz21PNr+ieAk75wGWfWHxf6K1xpeNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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