SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5257a9baa8981cb4c8a8f81399a91e1ad5f3004eeb20463e6ac2953167fe73f' 
  AND token = 'uSn2zHLWpbAhDJaysvjWgAj8Q4gn2SiFQBh7G5RXt+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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