SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83af1324102e66291a051474ee829b3d004045bbc1a303c66efca6f14dffc315' 
  AND token = '0qjdZl4xVYQ7lA+GN1BMWDuQ7xwUt/8YF2wb7QVWhgc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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