SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28220f758fc5c64c60522ab0c75be051e4ba2308eb5397e106647b1889cfb68b' 
  AND token = 'hiSS7SZ/PZbvWuJYdiBgDPRFKTbAg2dgBNdfkj2SbGc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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