SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa8eb52bab96e3b17a363f53029d8255ccdd6a2003dd7bdfec9f48404e176653' 
  AND token = 'h+dXh8q8rsSkt11dTxxZh9vbo7B8wUlKrxQ4AVhlrJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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