SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f50644f558f89cc0a8f7b0ae3c2727cbb51a10fb4c632073009bd593d25b0449' 
  AND token = 'uvGzFGliAiVTjXlgZgiQIFM6d0OIALu1AngNlqEWN9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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