SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2fd298c8146e1a2b27e85cb85568875be0606ea39fedee58161a68413a5786af' 
  AND token = 'dIndvj+bkDaGppk/QfS3SXmbjlpgR/qHLKuPoOhQoV8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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