SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c185b2051842cebd2d96052c3bffd0e665d520577dec1d8c6c3c95d6a424da6f' 
  AND token = '3U7cC1DpgsXPwL9Pn3QKm/Syp7pxGdfSzzeT5/g9yAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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