SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c6ed6940743df623b1746ad6b655815d44e03a4a3510567e031c6a53bee1b58' 
  AND token = 'bXddaFkgtQdOnzHHvbPkjrGHMXQWF1cxRDZd/Ejs+ww=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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