SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ad6d83ad69a0add27304be5d29a7f913235ad86186801bb067f8ad93b409de1' 
  AND token = 'KV0df/o9WJaPIIRRbO1hVKvmBDf54dVIrivqbbTRKrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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