SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8210152bd94da7b613cff0483aeefcb788ba5b4e8ab8c9054da0fe6d594daa48' 
  AND token = '9ZzYy8+iPC3UkpRzYJtBXR7v1opRw/mtMrZHnCZjKEI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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