SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68d7be2743793272e499843dff6347d36afff778b7408332054d74adb3a98576' 
  AND token = '1H1x9PozPxvCyrH+BzooayDSE+Xq8hrwQrOddXaJtwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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