SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3852430ee8393c7f34f2fd7824fcc6817142df05b222798420c659150639078' 
  AND token = 'TXDBTKRoJR20w6AeJURTnpBl9WhThPsIL8DtuZJxyVY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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