SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c53ceca03d066bca7b5184e74eca4f5740046acd92fb2445839f575735b16479' 
  AND token = 'D1qEFfhxgmVaDzlVCgB2Cb4ieUMGiy1UuKtVvSTETos=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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