SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '262bf18059d6e447281170beab52b5fd2578176be890a9d7882a923157533f41' 
  AND token = 'YCRRs2DPFToYJKhziwW7E41qZdE2qDfbhFyPiMImHOI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}