SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbd0821b4c9b691783bf30e06611948feb4f4f8540e079896c208409ad081559' 
  AND token = '/Z+CCbKhNd4RIXRCFsBD2sLGXHjrH5LMaDqNuExT5sw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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