SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec8e689692deb29675a1cd19bd9ad58b4a172df115b9bab189d137735ba6cdc4' 
  AND token = '6IfHjucEDl5l3k36aYgmS4oqyLK7jYYAZOTqMkuVX5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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