SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b15aa35cdb43fec814b1ece5b897627ea14a35c119901dea07b14c3326a3fcd' 
  AND token = 'kpZyuk0Ew/zTVrF+Sz9FSf2RqCPfj4Oww9IltneCp08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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