SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff3819ff295db970946fe235604e3183bafc93750b3d851f6a9b628f7b7bac57' 
  AND token = 'Q/94ObOKKW2UJUm3i1To/FRqbelkq+eZhGauulxswDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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