SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08509c3756bcafca4c5c46946784843a788518575597df6b08af00bef5f15743' 
  AND token = 'nw3O/zVCg5FvURFj3TDrE50h1rEAmGLH6tUiGHZskzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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