SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f6b94e0780a62a05f270008f2bc480238f626ca13b665142e94daf97a03505a' 
  AND token = 'IBN+y2hpyAWO8oR2p6zOKXNV6uBoihZFExBTpWvzM7M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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