SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81d217744c6ff20b8b4018cb7b7737c4efed078bb4095245914fdf08a53c7c73' 
  AND token = 'sSKsVLu1Nf7cqdPqQr3R6scXsBZRof9MjZOp5+GZoHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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