SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3959ef84f1faa4615035840bcb28193f91eb3b2cffa092bce52c67b47f7cf708' 
  AND token = 'KzwCMq+o3aoZieFvlDFSuAZilTUirah7WMM9eLQ8O00=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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