SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6439afebd8385069331a85e6f2abbef1f2e9818999f6174703d7e3af5d7ad5bb' 
  AND token = 'KGXeZPHKhyd2aF72emdcQCa9cIppgTauBEdWkt24gsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}