SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6926302ec8ed9964d44a160fcc0376960b1e09909902d79036622406fb36d83c' 
  AND token = '7dMw1n+7EdCmMWte9QTftwZXPpV8Hs5uQO6lHIsSjkc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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