SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3c6eda3f83f2f95e778882061adf31609395f766253a9542b3a2b84b554c0ce' 
  AND token = '5zQ/NPgibCkMmB2XZyiEeYYdDX2bKzU2hOTw8bkzNvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00007

JSON explain

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