SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b8e379bdb655ecbac4cd98cf21840058acc4fc1e6dcf8caa5028178f7b2f4f6' 
  AND token = 'tXjdIi+HFZdePCqiPBmLy/DC11wjwOE7beehfyxaYTI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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