SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3958053f2ca93dc1026bbd8504404af7883dc4f7a90298ee3072343eddc7398' 
  AND token = 'ai38sLLvxEZBGG1NrX2PfWFDYD0DmLuUaLxTGEAyh9c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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